Jake Arrieta Is Probably Okay

Last night, the Cubs saw their ace, Jake Arrieta, give up four runs in five innings in their Game Two loss to the Mets. Given how recently he seemed completely impossible to hit, it was bit jarring to see Arrieta struggle, and multiple observers noted during the game that his velocity appeared to be down from what he was throwing during the regular season. Jesse Rogers post-game recap on ESPN was even headlined “Jake Arrieta’s velocity dip spelled doom for Cubs…”

In discussing the issue with various Cubs after the game, Rogers noted that Joe Maddon saw it as well.

“In the game there, if that [radar] gun was correct on the field, he might have been down a mile an hour or two, that’s what I saw,” Cubs skipper Joe Maddon said. “And when that happens, the breaker, the commitment to the breaking ball is not as definite from the hitter’s perspective, because they’re able to see everything better.”

Arrieta himself noted that he knew his stuff wasn’t as good.

“I knew the high-end velocity wasn’t necessarily there tonight,” he said. “Threw quite a few changeups to offset that.”

He’s not kidding. After throwing just one change-up total in his previous two postseason starts, Arrieta fired off 10 change-ups against the Mets last night. The change-up isn’t a pitch he features much, as only about 5% of his total pitches this year were changeups. The fact that 11% of the pitches he threw were change-ups last night does suggest he didn’t trust his normal repertoire as much, and was looking for ways to get outs without his best stuff.

Including the postseason, Arrieta has now thrown 249 innings, so it’s natural to think that perhaps he’s wearing down after carrying a very heavy workload. And any time there’s a decline in velocity, it’s easy to jump to conclusions, especially if the results are worse than you’d expect as well. But, in this case, I wouldn’t be too quick to conclude that last night was proof that Arrieta is wearing down.

Most importantly, there’s the weather to consider. It was cold in New York this weekend, and game time temperature was just 45 degrees. As Mike Fast (among others) has previously shown, there is a very strong link between velocity and temperature.

Fast noted that his research showed a one mph difference in fastball speed for every 37 degree change in game-time temperature. Obviously, there hasn’t been that large of a difference in temperature between his last two starts, but game-time temperature was 68 degrees in Pittsburgh when Arrieta shut down the Pirates, and 73 degrees in Chicago for his start against the Cardinals. The game over game temperature decline from Arrieta’s last start was 28 degrees, so we probably shouldn’t be too surprised that his velocity was down relative to the last time he was on the mound.

Indeed, per Brooks Baseball, Noah Syndergaard’s velocity was also down last night, though not quite as visibly. In his start against the Dodgers, the Mets young flamethrower averaged 98.7 with his fastabll; last night, he averaged 98.3. The drop was a bit more noticeable on his curveball, when went from 82.4 to 81.2. Syndergaard was still throwing very hard last night, but the cold weather did seem to bring his velocity back down to earth a little bit as well.

So part of the velocity decline can be credited to the weather. And some of it is likely just random variation. While fastball speed is something that stabilizes very quickly, pitchers don’t throw precisely as hard in every single start all season long. In fact, Arrieta has already had a few big velocity declines like this earlier in the year.

On July 2nd, in a start against the Mets, Brooks’ recorded Arrieta’s sinker at an average of 97.2 mph. In his outing against the Cardinals five days later, it was just 95.2. Same thing in September; 96.6 against the Diamondbacks, then 94.7 against the Phillies. While Arrieta’s sinker velocity last night was his lowest of the season, a two mph drop from game to game isn’t unprecedented for him, and in each of the previous cases where he saw a big drop, he continued to pitch well and regained his velocity in subsequent starts.

And speaking of pitching well, it should probably be noted that he threw the ball far better than four runs allowed in five innings would suggest.

On the night, Arrieta faced 21 batters, and only six of them reached base, a .285 OBP allowed, and one of those six came when Joe Maddon ordered an intentional walk of Daniel Murphy. Ignoring the intentional walk, batters who swung the bat against Arrieta got on base at a .250 clip against him, only a few ticks north of the .236 OBP he allowed during the regular season. It’s not like he was constantly pitching out of trouble.

And he struck out 38% of the batters, so, even without his best stuff, it’s not like the Mets were consistently making contact against him. In reality, Arrieta started the game with two very poorly located pitches to Curtis Granderson and David Wright, and then Daniel Murphy hit a highly improbable home run on a curveball that was nearly in the dirt. Murphy didn’t exactly crush it, and to any other part of the ballpark, it’s a flyout, but because he hooked it right down the line, Arrieta ended up giving up three runs before he recorded an out.

But after that, he set down six straight, including four strikeouts, and then gave up his fourth run when a walk was followed by a couple of stolen bases and a single. This is one of those days when a 7.20 ERA doesn’t tell the story. If Arrieta had spread out his mistakes over his five innings of work instead of bundling them into the first and third innings, he probably only gives up a run or two. While he didn’t have his best stuff, the Mets only put up four runs against him because they were able to sequence their positive events in the most effective order possible.

Maybe some of that was because Arrieta didn’t have his best fastball last night, but more likely, that’s just baseball. It happens.

We can say that Arrieta didn’t have his best stuff last night. We can say that Arrieta gave up four runs last night. Both of those things are true. But I don’t know that we can connect those two facts that easily, and it’s probably an overstatement to say that Arrieta’s missing velocity doomed the Cubs in Game Two. Daniel Murphy hitting a ridiculous home run, and the Mets pitching staff being really freaking good are probably more of an accurate story to be telling this morning.

If Arrieta gets another chance to pitch in this series, it’s probably wise to bet on him both throwing harder and getting better results than he did last night. One start with a velocity dip (on a very cold night) where the opponents strung their hits together probably isn’t enough reason to get really worried about Jake Arrieta.