Frank Thomas or Mark McGwire? Ranking MLB's Top 20 First Basemen of the 1990s

In the weeks to come, we'll be taking a position-by-position look at the best MLB players of the 1990s. Who's ready for some nostalgia?

Up first, a stacked first base position.

A player's peak performance, his full statistical body of work during the 1990s and his postseason production were all taken into account when determining the final rankings.

While no single stat was the end-all, be-all in this conversation, OPS+ and WAR/500 are two important ones to know.

OPS+ is simply a hitter's on-base percentage plus slugging percentage, adjusted to take into account the ballparks in which he is hitting. An OPS+ of 100 is league-average, while each number above 100 represents one percentage point better than the league average.

WAR/500 is a stat of my own creation. It's simply a hitter's WAR total divided by his total plate appearances then multiplied by 500, thus giving us his WAR per 500 plate appearances. The idea is to make it easier to contextualize WAR totals across different sample sizes.

Let's kick things off with some honorable mentions.

These players received serious consideration for the final list but came up short:

• Tony Clark
• Kent Hrbek
• Don Mattingly
• David Segui
• J.T. Snow
• Paul Sorrento
• Kevin Young

Note: Jim Thome played more games at third base (492) than he did at first base (373) during the 1990s, so he will be included on the third basemen list.

Stats: 4,200 PA, .307/.361/.437 (112 OPS+), 73 HR, 495 RBI, 13.1 WAR

Postseason: 58 PA, .271/.368/.333, 0 HR, 5 RBI, One-time WS winner

WAR/500: 1.56

Hal Morris was the starting first baseman on the Cincinnati Reds team that won the World Series in 1990.

He hit .340/.381/.498 for a 136 OPS+ with 32 extra-base hits in 336 plate appearances that season to finish third in NL Rookie of the Year voting.

While he lacked prototypical first baseman power with a career high of 16 home runs in 1996, he was a perennial .300 hitter with solid on-base skills.

The four-player trade to acquire him from the New York Yankees prior to his rookie season stands as one of the better under-the-radar moves in Reds' history.

Stats: 3,100 PA, .269/.371/.479 (120 OPS+), 140 HR, 477 RBI, 13.2 WAR

Postseason: N/A

WAR/500: 2.13

A 14th-round pick in 1984, John Jaha took over as the Milwaukee Brewers starting first baseman in 1993 and produced a 103 OPS+ with 19 home runs and 70 RBI.

Despite his late start in the big leagues, his career spanned eight more seasons. However, he only stayed fully healthy for two of those, averaging just 56 games per year over the other six seasons.

On the rare occasion he was healthy, he was one of baseball's most productive sluggers:

• 1996: 148 G, 133 OPS+, 34 HR, 118 RBI
• 1999: 142 G, 152 OPS+, 35 HR, 111 RBI

His lone All-Star appearance came in 1999 when he made good on a minor league deal with the Oakland Athletics and hit a home run once every 13.1 at bats.

Stats: 4,337 PA, .279/.341/.446 (111 OPS+), 151 HR, 639 RBI, 10.3 WAR

Postseason: 100 PA, .267/.370/.453, 4 HR, 12 RBI

WAR/500: 1.19

Eddie Murray has a strong case for being the best first baseman of the 1980s.

When the new decade arrived, he was already 34 years old with 2,168 hits, 353 home runs and 1,278 RBI under his belt in 13 MLB seasons.

He hit .330/.414/.520 with 26 home runs and 95 RBI to win his third career Silver Slugger Award and finish fifth in NL MVP voting with the Los Angeles Dodgers in 1990. The following year he made his eighth All-Star appearance.

His production began to dip in the years that followed, but he remained a productive player throughout his late 30s and into his 40s.

The Hall of Famer tallied his 3,000th hit in 1995 and hit his 500th home run in 1996.

Stats: 2,719 PA, .267/.361/.531 (127 OPS+), 149 HR, 467 RBI, 11.3 WAR

Postseason: N/A

WAR/500: 2.08

Carlos Delgado checked in at No. 8 on our recent list of the 25 best first basemen since 2000.

One of the most hyped prospects of the 1990s during his time in the Toronto Blue Jays farm system, Delgado began his career as a catcher before moving to first base.

He replaced the departed John Olerud in 1997 and posted a 127 OPS+ with 30 home runs and 91 RBI that year. The following season he appeared on AL MVP ballots for the first time when he logged a 151 OPS+ with 38 home runs and 115 RBI, and he then won his first Silver Slugger Award in 1999 with 44 home runs and 134 RBI.

Those three seasons of peak production are enough to land him a spot on this list over guys who played a bigger chunk of the decade but made less of an impact.

Stats: 2,748 PA, .296/.381/.497 (128 OPS+), 106 HR, 418 RBI, 12.3 WAR

Postseason: N/A

WAR/500: 2.24

Jason Giambi also cracked the top 10 in our best first basemen since 2000 list, claiming the No. 7 spot.

He also faced the daunting task of replacing a franchise staple when he took over for Mark McGwire after he was shipped to St. Louis at the 1997 trade deadline.

After back-to-back 20-homer seasons while bouncing between first base, designated hitter and the corner outfield spots, Giambi posted a 130 OPS+ with 27 home runs and 110 RBI as an everyday player in 1998.

That was followed by a bona fide breakout season in 1999 when he finished eighth in AL MVP voting while hitting .315/.422/.553 with 36 doubles, 33 home runs and 123 RBI in a 5.9-WAR season.

He won AL MVP honors to kick off the 2000s, but the groundwork for that season was laid during the 1999 campaign.

Stats: 4,903 PA, .273/.329/.470 (114 OPS+), 211 HR, 734 RBI, 11.2 WAR

Postseason: 24 PA, .286/.375/.619, 2 HR, 4 RBI

WAR/500: 1.14

Eric Karros became the first of five straight Los Angeles Dodgers players to win NL Rookie of the Year honors in 1992, posting a 106 OPS+ with 20 home runs and 88 RBI while replacing Eddie Murray as the team's starting first baseman.

Over his first eight MLB seasons, he averaged 26 home runs and 92 RBI, and that included four seasons with at least 30 home runs and 100 RBI.

He stands out as one of the more productive players of the 1990s to never earn an All-Star selection, though he did garner MVP votes twice and take home Silver Slugger honors in 1995.

His overall value was limited by his middling on-base numbers and mediocre defense, but he was a productive middle-of-the-order power threat and run producer at a time when that was priority No. 1 at the first base position.

Stats: 5,050 PA, .292/.370/.436 (117 OPS+), 111 HR, 679 RBI, 22.5 WAR

Postseason: 47 PA, .179/.319/.256, 1 HR, 4 RBI

WAR/500: 2.23

Wally Joyner was a breakout sensation for the California Angels in 1986 when he became the first rookie to be voted to start the All-Star Game.

He was never quite able to live up to the lofty expectations of superstardom that debut created, but he settled in as a solid everyday first baseman over the course of a productive 16-year career.

He split the 1990s between the California Angels (two seasons), Kansas City Royals (four seasons) and San Diego Padres (four seasons), and while he averaged just 11 home runs and 68 RBI per season, his stellar on-base ability helped drive his offensive value.

At a time when strikeouts were on the rise, he tallied more walks (559) than strikeouts (545) over the course of the decade, which helped him post a strong .370 on-base percentage.

He was the starting first baseman for the Padres team that reached the World Series in 1998, ranking fourth on the team in OPS+ (124) and third in RBI (80).

Stats: 2,877 PA, .306/.402/.455 (136 OPS+), 59 HR, 375 RBI, 17.7 WAR

Postseason: 58 PA, .298/.431/.468, 1 HR, 9 RBI

WAR/500: 3.08

John Kruk played just four full seasons during the 1990s before the strike-shortened 1994 season and then the final season of his career in 1995.

His lack of elite-level power numbers kept him out of the upper echelon of first baseman during his peak, but it didn't stop him from making three straight NL All-Star teams from 1991 to 1993.

He ranked in the top 10 in the NL in batting average, on-base percentage and OPS+ during the 1992 and 1993 seasons:

• 1992: .323 BA (third), .423 OBP (second), 150 OPS+ (fifth)
• 1993: .316 BA (eighth), .430 OBP (second), 145 OPS+ (fifth)

He is one of 204 players in MLB history to tally at least 3,000 plate appearances and finish with a batting average of .300 or better.

Stats: 5,381 PA, .256/.349/.483 (120 OPS+), 288 HR, 924 RBI, 17.0 WAR

Postseason: 67 PA, .283/.358/.467, 3 HR, 15 RBI

WAR/500: 1.58

After four forgettable seasons with the Toronto Blue Jays, Cecil Fielder spent 1989 playing for the Hanshin Tigers in Japan where he parlayed a 38-homer season in to a two-year, $3 million contract from the Detroit Tigers.

In his stateside return in 1990, he became the first player since George Foster in 1977 to hit 50 home runs in a season. He led the AL in slugging (.592), home runs (51) and RBI (132) to finish runner-up in AL MVP voting. He led the AL in home runs (44) and RBI (133) again the following year.

All told, he averaged 37 home runs and 114 RBI with a 125 OPS+ over the first seven seasons of the decade before injuries and age started to catch up with him.

He was traded to the New York Yankees at the 1996 deadline, and he posted a 108 OPS+ with 13 home runs and 37 RBI in 53 games following the trade. He then homered twice in the ALCS and went 9-for-23 in the World Series to win his lone World Series ring.

Stats: 4,947 PA, .293/.349/.524 (120 OPS+), 255 HR, 859 RBI, 19.9 WAR

Postseason: 58 PA, .196/.293/.275, 1 HR, 6 RBI

WAR/500: 2.01

Andres Galarraga was already eight seasons into his MLB career when he joined the expansion Colorado Rockies in free agency during the 1992-93 offseason.

A career .267/.322/.432 hitter with three 20-homer seasons and a pair of Gold Glove Awards on his resume at that point, he was a solid addition to a fledgling franchise but by no means a star entering his age-32 season.

That quickly changed.

He hit .370/.403/.602 with 22 home runs and 98 RBI in his first season with the Rockies, claiming the NL batting title in the process—and that was just the start.

During the six-year span from 1993 through 1998, he posted a 131 OPS+ and averaged 36 home runs and 117 RBI, finishing in the top 10 in NL MVP voting five times. He also led the NL in home runs (47) and RBI (150) during the 1996 season.

The "Big Cat" was an imposing figure in the batter's box at 6'3" and 235 pounds, and he was at the heart of some lethal Colorado lineups in the 1990s.

Stats: 4,768 PA, .275/.347/.486 (116 OPS+), 213 HR, 798 RBI, 20.3 WAR

Postseason: 232 PA, .232/.341/.354, 5 HR, 22 RBI, Three-time WS winner

WAR/500: 2.13

Another player tasked with filling some big shoes, Tino Martinez was acquired by the New York Yankees prior to the 1996 season to replace the retired Don Mattingly.

At the time of the trade, Martinez was fresh off the best year of his six-year career. He posted a 135 OPS+ with 31 home runs and 111 RBI to earn his first All-Star selection during the 1995 season.

In his first four seasons with the Yankees to close out the decade, he averaged 30 doubles, 31 home runs and 122 RBI while posting a 120 OPS+ and 12.6 WAR.

He was part of three World Series winners during that four-year span and he finished runner-up in AL MVP voting in 1997 when he hit .296/.371/.577 for a 143 OPS+ with 44 home runs and 141 RBI.

It was the perfect trade at the perfect time for a Yankees team that was saying goodbye to a franchise icon.

Stats: 5,366 PA, .302/.382/.480 (129 OPS+), 165 HR, 783 RBI, 30.8 WAR

Postseason: 31 PA, .111/.226/.111, 0 HR, 0 RBI

WAR/500: 2.87

Will Clark enjoyed some of his productive seasons at the onset of his career in the late 1980s. Otherwise, he might have pushed even closer to a top-five spot in these rankings.

He was already a two-time All-Star and fresh off a runner-up finish in NL MVP voting when the 1990 season arrived, and he added four more All-Star appearances over the first five seasons of the decade.

After eight seasons with the San Francisco Giants, he joined the Texas Rangers in free agency prior to the 1994 season, replacing his old college teammate Rafael Palmeiro who had signed with the Baltimore Orioles.

With a smooth lefty swing and a terrific eye at the plate, Clark remained productive well into his 30s, and he wrapped up his 15-year career with a .303/.384/.497 line and 137 OPS+.

It's a bit surprising he spent just one year on the writers' Hall of Fame ballot.

Stats: 5,044 PA, .301/.390/.538 (138 OPS+), 263 HR, 860 RBI, 26.6 WAR

Postseason: 33 PA, .226/.273/.484, 2 HR, 7 RBI

WAR/500: 2.64

Mo Vaughn was one of the most productive sluggers in baseball and the face of the Boston Red Sox lineup during the 1990s.

In his seven full seasons during the decade, he posted a 144 OPS+ and averaged 35 home runs and 110 RBI, and that includes his numbers during the strike-shortened 1994 season.

He won AL MVP honors in 1995 when he hit .300/.388/.575 with 39 home runs and an AL-leading 126 RBI, and he finished in the top five in voting two other times while earning three All-Star selections.

The Anaheim Angels gave him a six-year, $80 million deal in free agency prior to the 1999 season, and he posted a 115 OPS+ with 36 home runs and 117 RBI in his first season with the team before injuries became an issue.

At his peak, Vaughn was as feared as any middle-of-the-order threat in baseball.

Stats: 6,467 PA, .310/.385/.449 (122 OPS+), 117 HR, 786 RBI, 36.1 WAR

Postseason: 12 PA, .083/.083/.083, 0 HR, 1 RBI

WAR/500: 2.79

Mark Grace is often lost in the shuffle at a position loaded with prototypical sluggers during the 1990s.

That said, he was a significant offensive threat in his own right, thanks to a contact-driven approach and impressive durability. To that point, here's a look at the hit leaders of the 1990s:

• Mark Grace: 1,754
• Rafael Palmeiro: 1,747
• Craig Biggio: 1,728
• Tony Gwynn: 1,713
• Roberto Alomar: 1,678

Grace never hit more than 17 home runs in a season, but his .310 average was good for eighth among players with at least 3,000 plate appearances during the 1990s.

He was also a four-time Gold Glove winner, and he had the tall order of protecting Sammy Sosa in the lineup during his 66-homer season in 1998.

Stats: 5,699 PA, .301/.406/.482 (134 OPS+), 172 HR, 762 RBI, 39.8 WAR

Postseason: 158 PA, .304/.386/.442, 5 HR, 24 RBI, Two-time WS winner

WAR/500: 3.49

The Toronto Blue Jays traded Fred McGriff and Tony Fernandez to the San Diego Padres in exchange for Roberto Alomar and Joe Carter prior to the 1991 season. It's a deal that was made possible by a rising star named John Olerud.

A third-round pick in 1989 after one of the most productive college careers of all time, Olerud jumped straight to the majors after signing and served as Toronto's starting DH in his age-21 season in 1990.

His presence no doubt helped the front office come to terms with the idea of trading an All-Star slugger like McGriff. Olerud was not the same power threat, but he effectively replaced his offensive production in other ways.

To that point, there were just 10 seasons during the 1990s of a player hitting at least .350/.440/.550 while qualifying for the batting title. Frank Thomas did it once. Jeff Bagwell did it once. John Olerud was the only first baseman to do it twice.

His best season came in 1993 when he led the AL in batting average (.363), on-base percentage (.473), OPS (1.072), OPS+ (184) and doubles (54). He was a 7.8-WAR player and finished third in AL MVP voting.

Stats: 6,255 PA, .291/.381/.514 (135 OPS+), 300 HR, 975 RBI, 32.7 WAR

Postseason: 197 PA, .323/.411/.581, 10 HR, 34 RBI, One-time WS winner

WAR/500: 2.61

Fred McGriff was a consistent middle-of-the-order presence throughout the 1990s.

He spent time with the Toronto Blue Jays, San Diego Padres, Atlanta Braves and expansion Tampa Bay Devil Rays during the decade, averaging 30 home runs and 98 RBI per season.

The Braves acquired him from the Padres at the 1993 deadline, and he hit .310/.392/.612 for a 165 OPS+ with 19 home runs and 55 RBI in 68 games following the trade. He recorded 130 home runs and made three All-Star appearances in parts of five seasons in Atlanta, helping launch a perennial contender that won 14 consecutive division titles from 1991 to 2005.

He joined the Devil Rays for their inaugural season in 1998, and the following year he had a season that still stands as one of the most productive in franchise history, hitting .310/.405/.552 with 30 doubles, 32 home runs and 104 RBI.

His 300 home runs during the 1990s were tied for 10th among all players.

Stats: 6,681 PA, .299/.375/.534 (139 OPS+), 328 HR, 1,068 RBI, 49.7 WAR

Postseason: 91 PA, .244/.308/.451, 4 HR, 8 RBI

WAR/500: 3.72

Rafael Palmeiro steadily developed into one of the most prolific sluggers in baseball as the 1990s progressed.

After hitting 122 home runs from 1990 through 1994, he posted a 138 OPS+ and averaged 41 home runs and 125 RBI over the final five seasons of the decade, winning a pair of Silver Slugger Awards and earning a pair of All-Star nods during that span.

He had nine seasons of at least 4.0 WAR during the decade while playing with the Texas Rangers and Baltimore Orioles, and he also received MVP votes nine times.

Playing alongside Juan Gonzalez, Ivan Rodriguez, Jose Canseco, Dean Palmer and Julio Franco, Palmeiro was part of some of the most prolific lineups of the 1990s.

If only they had some pitching.

Stats: 5,800 PA, .304/.416/.545 (160 OPS+), 263 HR, 961 RBI, 56.9 WAR

Postseason: 48 PA, .128/.292/.128, 0 HR, 4 RBI

WAR/500: 4.91

Acquired in one of the most lopsided trades in MLB history, Jeff Bagwell burst onto the scene for the Houston Astros in 1991 when he hit .294/.387/.437 for a 139 OPS+ with 15 home runs and 82 RBI to win AL Rookie of the Year honors.

Three years later, he added NL MVP to his resume by hitting .368/.451/.750 for a 213 OPS+ with 39 home runs and an AL-leading 116 RBI in 110 games.

He went on to post a pair of 30/30 seasons in 1997 (43 HR/31 SB) and 1999 (42 HR/30 SB), a rare feat for a first baseman. The only other player in MLB history to do it while playing primarily first base was Joe Carter in 1987, when he had 32 home runs and 31 steals.

His .416 on-base percentage for the decade trailed only Barry Bonds' (.434) and Edgar Martinez's (.430) among players with at least 3,000 plate appearances.

It might be a long time before we see another first baseman with his combination of power, speed and on-base ability.

Stats: 5,054 PA, .268/.411/.615 (173 OPS+), 405 HR, 956 RBI, 46.4 WAR

Postseason: 60 PA, .170/.339/.234, 1 HR, 5 RBI

WAR/500: 4.59

If not for an injury-plagued stretch from 1993 to 1995 when he played just 178 total games, Mark McGwire would have a compelling case for the No. 1 spot in these rankings.

With a 49-homer rookie season in 1987 and a 42-homer season in 1992 when he led the AL in OPS+ (176) and slugging (.585), he was already well-established as one of the game's biggest power threats when he took aim at the record books during the second half of the decade.

After a 52-homer season in 1996, he launched another 58 home runs in 1997, including 24 long balls in 51 games with the St. Louis Cardinals following a midseason trade.

That was followed by his record-breaking 70-homer season when he also led the NL in OPS+ (216), walks (162) and on-base percentage (470). For good measure, he led the NL in home runs (65) and RBI (147) again in 1999.

All told, "Big Mac" led the majors with 405 home runs during the 1990s, earning eight All-Star nods and finishing in the top 10 in MVP voting four different times.

Stats: 6,092 PA, .320/.440/.573 (169 OPS+), 301 HR, 1,040 RBI, 52.8 WAR

Postseason: 27 PA, .353/.593/.529, 1 HR, 3 RBI

WAR/500: 4.33

If Ken Griffey Jr. was the face of baseball during the 1990s, Frank Thomas was a close second.

The "Big Hurt" was the No. 7 overall pick in the 1989 draft, and he debuted the next year, hitting .330/.454/.529 with seven home runs and 31 RBI in a 60-game audition.

That was followed by a seven-year stretch that few hitters in MLB history can rival.

From 1991 through the 1997 season, he hit .330/.452/.604 for a 182 OPS+ while averaging 34 doubles, 36 home runs, 118 RBI and 6.4 WAR.

He won back-to-back AL MVP Awards in 1993 and 1994, and he won the AL batting title in 1997 when he hit .347/.456/.611 with 35 home runs and 125 RBI en route to a career-high 7.3 WAR.

There's a strong case to be made that Thomas at his peak was the greatest right-handed hitter in MLB history, and that's enough to earn him the No. 1 spot in these rankings.

All stats courtesy of Baseball Reference and FanGraphs, unless otherwise noted.