Watch a ballgame or engage in a discussion about the sport, and there's a good chance you'll hear the phrase "back of the baseball card" uttered somewhere along the line.

The term is often used to explain that a streaking or slumping player will eventually perform somewhere in line with his career numbers, which can be found—you guessed it—on the back of his baseball card.

It can also be used to convey respect toward a player by saying something like, "The back of Albert Pujols' baseball card speaks for itself."

That second application is true: The numbers on the back of a baseball card can tell us a lot about a player. Pick up a Topps or an Upper Deck, flip it over, and—voila—you can find out what a player's career batting average is, the most RBI he tallied in a single season and how many errors he's made.

But maybe it's time to put a new spin on this age-old expression by altering the statistics printed on the back of baseball cards.

With the rise in popularity and accessibility of sabermetrics over the past decade or two, the way the sport is being evaluated has changed—statistics like batting average, RBI and errors have lost some ground to many advanced metrics.

Even though the baseball card industry isn't necessarily thriving like it once did a generation or two ago, the "back of the baseball card" phrase is still a part of the sport's lexicon. That's perfectly fine—it's a charming little idiom—but in the interest of keeping up with the times, perhaps the numbers, digits and figures that are on the other side of the player's picture should be...updated.

Obviously, all basic info, such as team, date of birth, weight and height won't be going anywhere, and there's probably still enough room to include one or two of those "fun facts." But otherwise, what follows is a crack at the stats and metrics that *should* be the ones alluded to whenever someone says "back of the baseball card."

**For Hitters**

**Games (G): **It's as simple a stat as there is, but it's helpful to know how much a player actually, you know, plays.

**Plate Appearances (PA): **Plate appearances instead of at-bats, because many of the rate statistics below actually come from using PA instead of AB, a stat that doesn't include walks, sacrifice flies and hit-by-pitches.

**Batting Average/On-Base Percentage/Slugging Percentage (BA/OBP/SLG): **Because on-base percentage and slugging percentage better indicate how effective a batter is, they need to be presented along with batting average in the ideal "triple-slash" manner.

**Runs (R): **This stat is still the name of the game.

**Doubles/Triples/Home Runs (2B/3B/HR): **Similar to the triple-slash stats, it's helpful to see the counting totals for doubles, triples *and* homers right alongside each other.

**Stolen Bases/Caught Stealing (SB/CS):** This way, it's clear exactly how frequently a player attempts a stolen base—and how frequently he's successful.

**Batting Average on Balls in Play (BABIP): **The first new-age metric listed, BABIP measures how many of a batter's balls in play go for hits. For context, the league-wide average is usually around .295-.300, and the prevailing thought is that most players' BABIPs will eventually regress to that mean.

Any player whose BABIP is well above that (i.e. .330 or higher) is likely to eventually see his batting average drop, while any player who is well below that (i.e. .260 or lower) is likely to eventually see his batting average rise.

**Walk Percentage/Strikeout Percentage (BB%/K%): **In short, the former (BB%) is the percentage of plate appearances in which a player walks, and the latter (K%) is the percentage of plate appearances in which a player strikes out. For context, a BB percent of eight is about average, with anything higher than that above average, while a K percent of about 18-20 is average, with above average being anything below that.

** Ultimate Zone Rating/Defensive Runs Saved (UZR/DRS): **Move over, errors! UZR includes factors like range, arm and errors to produce a counting metric that puts a run value to defense, where zero is average, anything higher than that is above average (15-20 is elite) and anything lower is below average.

DRS, meanwhile, is based on adding and subtracting the number of times any given play is made (or not made) by a player at a position compared to the average at that position. Like UZR, zero is average, and anything higher is above average (15-20 is elite). (Both UZR and DRS are compiled by Baseball Info Solutions.)

**Wins Above Replacement (WAR):** An all-encompassing advanced metric, WAR may, in fact, be the best and easiest statistic for measuring and quantifying the value any given player brings to his team based on all of his contributions across all facets of baseball—including hitting, pitching, baserunning, defense, etc. A WAR of 2.0 is about average, with anything higher being above average, and anything 6.0 or better signifying MVP-caliber.

To help visualize the 10 categories above, here's a sample of what the back of Mike Trout's baseball card would look like:

Season | G | PA | BA/OBP/SLG | BABIP | BB%/K% | R | 2B/3B/HR | SB/CS | UZR/DRS | WAR |

2013 | 122 | 560 | .333/.430/.574 | .376 | 13.8%/17.0% | 88 | 34/8/21 | 28/4 | 3.2/-9 | 8.6 |

Career | 301 | 1334 | .317/.400/.549 | .366 | 11.5%/19.8% | 237 | 67/15/56 | 81/9 | 9.2/14 | 19.3 |

FanGraphs

You'll notice that RBI are not listed above. This is not an oversight.

While that statistic could easily enough be included, it's also a flawed number that is based more on a player's surrounding lineup (i.e. how often players ahead of him get on base) as well as his ability to drive in runs in such situations (which doesn't show much year-to-year correlation).

This exercise isn't all about adding new stats into the back of baseball cards—it's about eliminating some, too.

**For Pitchers**

**Games/Games Started/Innings Pitched (G/GS/IP):** Presenting these three stats in slashed succession helps to quickly and clearly assess whether the pitcher is a starter or reliever and how many innings he throws per outing.

**Earned Run Average/Fielding-Independent Pitching (ERA/FIP):** This is a mix of old-school and new-school stats displayed adjacently. ERA is a staple stat, but FIP, which is scaled to look like ERA and is based on factors that are under a pitcher's control (strikeouts, walks, home runs), is a better indicator of actual performance.

A pitcher with an ERA well below his FIP likely has been lucky to an extent, whereas a pitcher has likely been unlucky if his ERA is higher than his FIP.

**Walks and Hits Per Innings Pitched (WHIP): **This one became popular around the turn of the century, and it's still a good sign of how many baserunners a pitcher is allowing per inning.

**Batting Average Against (BAA):** Another stat that has been around for a long time, BAA is basically batting average—the number of hits allowed divided by the number of at-bats—but for pitchers.

**Batting Average on Balls in Play (BABIP): **See above for the explanation of the metric. As for context, it's the opposite for pitchers compared to hitters: A pitcher with a BABIP that is far below league average (i.e. .260 or lower) will see his BAA start to rise as more hits fall in, but a pitcher whose BABIP is far above league average (i.e. .330 or higher) will see his BAA drop eventually.

**Strikeout Percentage/Walk Percentage (K%/BB%): **While strikeouts per nine (K/9) and walks per nine (BB/9) may be more familiar, K% and BB% are more useful and telling, because they use the total number of batters faced (and not innings pitched) as the denominator when it comes to determining how often a pitcher strikes out or walks the opposition. For context, 18.0 percent is average for a strikeout rate, while eight percent is average for a walk rate.

**Home Runs Per Nine (HR/9): **Fairly straightforward, this is how many home runs a pitcher surrenders per nine innings. This makes it easier to compare two starters who have a large disparity in the number of innings pitched, or even to compare a starter to a reliever. Anything around 1.0 is average.

**Ground-Ball Percentage/Fly-Ball Percentage (GB%/FB%): **In recent years, there's been more of an emphasis on batted-ball data. In general, it's preferable for pitchers to get more grounders and fewer fly balls (which are more likely to turn into extra-base hits and/or home runs). In general, a GB percent of 45 percent is about average, and the elite ground-ballers are north of 50 percent.

**Shutdowns/Meltdowns (SD/MD): **Forget saves! Shutdowns and meltdowns are the newest of all the statistics mentioned in this piece, but they need to catch on quickly so saves aren't the be-all and end-all when it comes to evaluating relievers.

As FanGraphs explains it, SD and MD essentially answer the question: "Did a relief pitcher help or hinder his team’s chances of winning a game?" It's a little more complicated than that—and requires knowledge of another metric, Win Probability Added (WPA)—but it's arguably easier to comprehend than the oddly defined save statistic, and it's a truer measure of reliever effectiveness, since it puts closers on equal footing with all other relievers. Contextually, shutdowns are similar to saves (30-plus is elite).

**Wins Above Replacement (WAR): **See above for the explanation of and context for the metric.

Again, for the more visual learners, this is how Matt Harvey's card would appear:

Season | G/GS/IP | ERA/FIP | WHIP | BAA | BABIP | K%/BB% | HR/9 | GB%/FB% | SD/MD | WAR |

2013 | 25/25/175.2 | 2.25/2.00 | 0.89 | .196 | .268 | 28.4% | 0.4 | 47.3%/33.0% | 0/0 | 5.9 |

Career | 35/35/231 | 2.38/2.33 | 0.96 | .195 | .267 | 28.5% | 0.5 | 45.1%/34.1% | 0/0 | 7.1 |

FanGraphs

One prominent pitcher statistic was missing. Did you notice?

That's right: wins.

Sorry, but pitcher wins (and losses) is perhaps the flukiest, flimsiest stat in baseball. There are too many outside factors that can influence whether a pitcher registers a win or loss.

The other metric that would be worthwhile to include for pitchers is left on-base percentage (LOB%), but in the interest of keeping the backs of these revamped baseball cards uniform, let's stick with an even 10 stats for both hitters and pitchers.

At least for now.

There are already plenty of changes and alterations proposed above—any more, and we might have to suggest the stick of chewing gum be added back into packs of baseball cards.

*What statistics belong on the back of baseball cards? State your case in the comments.*

*All statistics, metrics and definitions come from FanGraphs.*