Carlos Martinez Will Take a Huge Step Back After the All-Star Break

It’s hard to imagine 2015 going any better for St. Louis Cardinals starter Carlos Martinez. A 10-3 record and 2.52 ERA led the young right-hander to his first All-Star Game. But Martinez is likely going to take a major step back throughout the rest of the season.

The good fortune of Martinez began in the offseason, when St. Louis traded away Shelby Miller, opening up a rotation spot for the young right-hander. The Cardinals put CarMar’s locker next to catcher Yadier Molina's in spring training in hopes that he would learn from the veteran backstop.

It seems that the move has paid major dividends for Martinez. But great success in baseball often comes with a side of regression, and CarMar is due for a heaping helping.

The most obvious reason Martinez is due to take a step back is his innings. Martinez is already at a career-high 107.1 innings pitched.

Typically, when pitching prospects start their first full season, we begin to see regression in the second half because they’re not used to throwing so many innings. Minor league seasons are about a month shorter than MLB seasons, which often leads to overuse and fatigue in young arms.

Martinez isn’t a pitching prospect anymore. But this is the first season he’s started consistently.

That isn’t to say that Martinez is going to blow up and get sent back to the bullpen. But he could end up back in the bullpen without a complete blowup.

The Cardinals could decide to cap Martinez’s innings and put him back in a late-inning relief role like last season. Although it seems unlikely, given their place in the standings, the Cardinals do have other arms available to start in Martinez’s stead.

And the St. Louis Post-Dispatch’s Derrick Goold reported back in April that the team would limit both Martinez's and Michael Wacha’s innings:

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Martinez has never pitched more than 120 1/3 innings total in a season, including his work in the minors. Both Matheny and Mozeliak mentioned that his winter ball innings should be factored into his experience to inflate that number. Still, Mozeliak conceded that a jump to 150 innings and "getting in that range would be a fair question."

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Underlying statistics could play a role in Martinez’s perceived step back. The law of averages should be a major concern to Cardinals fans and CarMar’s fantasy owners.

A 2.52 ERA and a rate of 9.48 strikeouts per nine innings are the best of Martinez’s short career. The K/9 stat is particularly interesting, given that relievers tend to post higher numbers for that stat, and prior to this year, Martinez had made only eight career starts.

Martinez’s K/9 rate can likely be attributed to a better mixing of his pitches. He’s throwing his changeup twice as often as he did last season and has cut down the use of his fastball from over 50 percent of the time in his first two seasons to just 34.9 percent this year. A lot of that is likely the result of his need to maintain stamina as a starter rather than just rearing back and letting it go in relief.

Martinez’s walk rate, however, is slightly above the MLB average at 3.61 walks per nine innings. While it’s not anything to be alarmed about, it is something to keep an eye on, as Fox Sports Midwest noted back in May.

Central to Martinez’s likely regression are three stats: batting average on balls in play (BABIP), fielding independent pitching (FIP) and left-on-base percentage.

We’ll start with BABIP. Martinez’s BABIP is .287, which again isn’t far below average. The issue with CarMar’s BABIP is twofold and simple.

First, Martinez’s BABIP this season is well below his rate from the previous two MLB seasons, which means it could be an outlier.

2013	.345
2014	.333
2015	.287

Second, Martinez has pitched so well that it won’t take much for him to regress. In other words, he’s been so good that expecting him to keep it up is a long shot.

Martinez’s FIP is 3.47, which is slightly better than average. Again, nothing sticks out against Martinez here, except that his FIP is almost a full point higher than his ERA, so it would stand to reason that regression is coming.

Saying that Martinez’s FIP is slightly better than average is a good thing, except that his ERA is much better than average. The two don’t match up in terms of agreement, and it’s likely that the ERA will begin to correct itself at some point.

This leads to the main reason why Martinez will come back down to earth: his left-on-base percentage.

Player	LOB%	ERA
1. Zack Greinke (LAD)	89.5%	1.39
2. Hector Santiago (LAA)	88.9%	2.33
3. Carlos Martinez (STL)	85.8%	2.52

According to FanGraphs, an 80 left-on-base percentage is excellent. This video by Bradley Woodrum humorously shows why Martinez and his incredible 85.8 left-on-base percentage are going to be eaten by the Luck Dragon.

The good news is that CarMar is off to such a hot start that saying he’s going to take a huge step back doesn’t necessarily mean he’s going to fall off a cliff in terms of production. He could still be a valuable commodity for the rest of the season, but a 2.52 ERA is highly improbable. Expect something closer to a 3.15 mark by season’s end.

All stats courtesy of FanGraphs unless otherwise noted.

Follow Aaron Brand on Twitter @AaronBrand47.