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Carlos Carrasco's ERA says he hasn't pitched well, but his ERA doesn't know

Has Carrasco pitched well so far this year? That depends on which metric you ask.

Rick Osentoski-USA TODAY Sports

Carlos Carrasco has had a very eventful last month. The day before the season began it was announced that he'd agreed to a long-term extension with the Indians, which guarantees him more than $20 million and could keep him in an Indians uniform through 2020 if the team decides to exercise both of its options on him. Then, barely a week later, he was struck in the face by a line drive. He was incredibly fortunate to suffer nothing worse than bad bruising, and was able to return to the mound only seven days later. Those two big events have kept me from thinking as much as I otherwise would have about how he's actually pitched.

Looking at his numbers, you can tell yourself Carrasco has been whatever type of pitcher you want.

If you think he's struggling under the pressure of his new contract, or badly shaken by that come-backer, you can look at his unsightly ERA of 4.98.

If you think he's proving the end of last season was a legitimate sign that he's become a different pitcher, you can look at his very impressive FIP of 2.61.

That ERA ranks 46th among the 68 American League pitchers with 20+ innings so far this season, while the FIP ranks 5th.

As with most instances of two different measures giving very different takes on a player, the truth likely lies somewhere in the middle, but how is it that the two numbers can be that far apart?

First, what is it FIP loves about Carrasco? Well, as you probably know, FIP is really only interested in strikeouts, walks, and home runs, the things a pitcher has the most control over. Carrasco's HR rate (0.83 HR/9) and walk rate (2.49 BB/9) both rank 30th among those 68 pitchers, so he's in the top half, but basically near the middle. Carrasco has already recorded 29 strikeouts though, giving him a rate of 12.05 K/9. That's a steller figure, which ranks 2nd in the AL behind only that of his teammate Danny Salazar.

In case you're wondering, only three pitchers in MLB history have ever had a full season with a strikeout rate that high: Kerry Wood did it in his rookie season of 1998, Pedro Martinez did it in his otherworldly 1999, and Randy Johnson did it six times during his otherworldly career. Wood's 129 ERA+ was the lowest from among those eight seasons, which is to say that when a pitcher is striking batters out at Carrasco's current rate, they've always been having a really good year. Of the top 40 seasons in MLB history for strikeout rate (which includes all seasons with a K/9 of 10.42 or better), not a single one of them has featured a below average ERA+. Only one of them has included an ERA+ lower than 112.

If Carrasco comes anywhere near maintaining his strikeout rate, his ERA is either going to get a lot better, or he's going to make history.

What's keeping his ERA from being better? It's the thing a pitcher has much, much less control over: Balls in play. Carrasco's BABIP allowed is currently .407, which is the highest of any of those 68 pitchers I mentioned already. (The full AL BABIP right now is.)

In case you're wondering, the highest single-season BABIP allowed by a pitcher with 150+ innings  in American League history is .355, suffered by Kevin Brown in 1994, as offense was exploding league-wide.

Whether Carrasco keeps striking guys out at his current rate or not, his BABIP is either going to drop substantially or he's going to make history.

So, look at it this way, either Carrasco is going to start allowing a lot fewer runs, or we're going to see something we've never seen before. Win-win, right?