Ranking the 5 Most Underrated Prospects in the Seattle Mariners' System

The Seattle Mariners’ farm system is one of the best in the game, with a majority of their top prospects stashed at Double-A or above. Although the on-field product at the major league level has been generally uninspiring, the organization has done an admirable job drafting both high-ceiling and high-floor talent over the last three years.

Headed into the 2013 season, the Mariners have an impressive collection of top 100 prospects in RHP Taijuan Walker, C Mike Zunino, LHP Danny Hultzen, SS-2B Nick Franklin and LHP James Paxton. Beyond those players, their system is exceptionally deep and loaded with potential impact talent—including several under-the-radar prospects.

In selecting players for this article, I targeted prospects who are behind the developmental curve relative to their age, have a concerning medical history, lack significant professional experience or are simply underappreciated. 

Here’s a look at the most underrated prospects in the Seattle Mariners’ farm system.

5. Patrick Kivlehan, 3B

A four-year football player at Rutgers (defensive back), Patrick Kivlehan made a triumphant return to the baseball field as a college senior, which ultimately led to his selection in the fourth round last June.

Assigned to the Short-Season Everett to open his professional career, Kivlehan was named the Northwest League’s MVP after batting .301/.373/.511 with 32 extra-base hits (12 home runs), 14 stolen bases and 93/19 K/BB.

At 6’2”, 210 pounds, Kivlehan is high-level athlete with raw baseball skills. At the plate, the right-handed hitter has above-average raw power, but he also swings through too many pitches. Albeit explosive, his swing can get long and tight, which, in turn, hinders consistent contact.

Given his football background, Kivlehan doesn’t possess the speed one might expect. However, he does have quick feet as well as excellent instincts—both of which should help him adapt to the hot corner in the minor leagues. His lack of arm strength is slightly concerning and may prompt a move to left field or first base down the road.

4. Brandon Maurer, RHP

Of all the Mariners’ highly regarded pitching prospects, including Taijuan Walker, Danny Hultzen and James Paxton, Brandon Maurer is arguably the closest to contributing in the major leagues. A 23^rd-round pick in the 2008 draft, the 6’5” right-hander has been slow to develop, but he made significant adjustments last season.

Maurer was exceptional last season at Double-A, as he registered a 3.20 ERA and .244 BAA with 117/48 K/BB in 138 innings. His performance was especially encouraging after a poor showing (4.99 ERA, 1.1 HR/9) in 2011.

His fastball consistently registers in the low-to-mid-90s with excellent late action to the arm side, while his slider is an above-average-to-plus pitch that serves as his out pitch and generates plenty of whiffs. Maurer’s changeup has developed favorably, and he threw it with confidence in 2012. His curveball is an average offering and seems to be more of a show-me pitch at the moment.

3. Stefen Romero, 2B

A 12^th-round selection in 2010 out of Oregon State, Stefen Romero has absolutely mashed at each minor league stop. Last season, he was named the Mariners’ minor league player of the year after batting .352/.391/.599 with 34 doubles, 23 home runs, 101 RBI and 12 stolen bases in 116 games between High-A High Desert and Double-A Jackson.

I was very impressed by how the ball jumps off Romero’s bat in my look last season. His swing is smooth and efficient, and he benefits from quiet load and excellent timing. His direct bat path allows for extension after contact, and the ball gets small in a hurry when he squares it up.

It’s doubtful that he’ll sustain a high BABIP (batting average on balls in play) as he reaches higher levels, including the major leagues, so he’ll be forced to coax more walks.

Romero lacks typical second-baseman size at 6’3”, 225 pounds, and he has a body type that’s better suited for a corner position. At the same time, if he can at least provide adequate defense at the keystone, his bat could be a premium.

Overall, he’s an average defender with a good glove but lacks range. His biggest defensive asset is above-average arm strength, which could help get his bat in the lineup at a corner position sooner rather than later.

2. John Hicks, C

Signed as a fourth-rounder out of Virginia in 2011, John Hicks batted .312/.351/.472 with 49 extra-base hits and 22 stolen bases last year in his full-season debut for High-A High Desert (in the hitter-friendly California League).

He won’t hit for that much power, but his hit tool is promising, and he offers above-average speed relative to the position. His receiving is still raw, but his strong arm has led to a 51 percent caught-stealing rate through his first 136 games behind the dish.

1. Brad Miller, SS

Selected in the second round of the 2011 draft out of Clemson, Brad Miller, like teammate Stefen Romero, has posted gaudy offensive numbers since entering the Mariners’ system.

The left-handed hitter spent most of the 2012 season at High-A High Desert where he batted .339/.412/.524 with 49 XBH, 19 SB and 79/52 K/BB before he received a midseason promotion to Double-A Jackson. Despite the jump to the higher level, Miller didn’t skip a beat, as he batted .320/.406/.476 with 13 XBH and 26/22 K/BB.

A 6’2” left-handed hitter, Miller showcases a line-drive swing with excellent bat-to-ball skills. He doesn’t try to do too much at the plate, as he allows the ball to travel and lets hands work. He has above-average raw power, but doesn’t always tap into it.

Regardless, he’s an extra-base machine capable of hitting 50 doubles over a full season. His biggest asset may be his plate discipline, though, as he has an excellent feel for the strike zone. Miller’s speed is slightly above average, and he should have no problem swiping 20 bags in a given season.

Miller made noticeably improvements on defense last season and has the instincts, actions and quick feet to stick at up the middle.

He possesses a strong arm but lacks a consistent release point (36 errors in 2012), and will need to trim down the error totals in his ascent to the major leagues. If not, his (left-handed) bat-speed combo still offers upside at either any infield position.