The Yankees Bet on Brandon McCarthy and xFIP

The Yankees just pulled a rare feat by trading Vidal Nuno to the Diamondbacks for Brandon McCarthy. Only once in the last five years has a team traded for a pitcher whose results were so out of whack with their process and peripherals. Of course, that was when the Dodgers traded a player to be named later to the Phillies for Joe Blanton in 2012, but the Yankees have a few reasons to believe that this will turn out better for them than that trade did for the Dodgers.

ERA does not tell the full story of Brandon McCarthy’s season so far. Look across his line, and you see career-best strikeout (20%) and ground-ball rates (55.3%) paired with his customary excellent command… and then you see that he’s giving up twice as many home runs on fly balls as he has his whole career.

Let’s focus first on the stats by themselves, without context. We can look at his xFIP for short-hand on his walk, strikeout and fly-ball rates, and we can see a career-best number there. And we can see the big gap between his ERA and xFIP. And we can look for the 20 other qualified starting pitchers that have had the biggest such gaps in the first half. And we can create this list:

Obviously, it takes a confluence of track record and bad luck to get on this list. If you haven’t shown some promise, you’re not going to continue getting chances. But these pitchers also had terrible numbers in the parts of the game where they haven’t been shown to have great control over results. This group’s strand rate (65.2%) and home run per fly ball rate (14.2%) in particular, are well above the league’s number (generally 70% and 10% in any given year). And not in a big enough sample to believe they’ve earned those numbers.

So what did this group do in the second halves after their disastrous starts?

Better. Their collective ERA dropped a full run, as did the gap between their xFIP and ERA. They gave up fewer home runs, too, on a more normal home run per fly ball rate. Their strand rate regressed to league average. Their batting average on balls in play even regressed to a league average number.

There are two caveats here, however:

1. There’s a bit of survivor bias; due to injury, Jake Arrieta didn’t pitch in the second half in 2012, for example. Joe Blanton was on this list twice but was released once by the Angels after his poor early season in 2013. Pitchers who might not have regressed, for one reason or another, could have been prohibited from giving that non-regressing performance, thus skewing the numbers a bit.

2. The group’s results improved significantly, but they still underperformed their second xFIP by three-tenths of a run, and their second half xFIP was worse than their first half xFIP. In other words, players that underperform to this degree for half a season aren’t likely to continue to underperform to that same level, but they might be likely to still underperform, and you shouldn’t expect their second half performance to match their first half peripherals.

Of course, the Yankees would probably take a 4.30 ERA from their new pitcher, who might also welcome that number after his rough start. Especially given that the cost was minimal, and McCarthy has a track record of success that suggests that a poor three months probably doesn’t mean that he’s now permanently terrible.

For one, McCarthy’s xFIP is the best on that list above. His combination of stellar walk and ground-ball rates is really only equalled by Rick Porcello in 2013. And it’s built on a compelling back story — McCarthy bulked up this offseason in an effort to have more staying power, and in return, his velocity increased to a career high.

And though McCarthy has been looking for a better change up ever since he switched to featuring the sinker, his home run problem this year hasn’t been a function of a platoon split. He’s had a better strikeout, walk and home-run rate against lefties than righties this year. Not that the split is sustainable — he still has slightly worse numbers against lefties than righties for his career — just that lefties can’t be blamed for his homer rate this year. Perhaps the 11 home runs he’s given up in the hitter friendly parks in Arizona and Colorado (versus the four he’s given up elsewhere) have a little more to do with the ledger standing as it does.

At least the Yankees and their home park — third-friendliest in the league to lefty power hitters — can hope so. They’ve got the rest of the (non-ERA) numbers on their side, it looks like.