The most promising sign from Masahiro Tanaka’s past three starts

For the first several weeks of the season, everything was going right for the Yankees. Prospects were flourishing upon reaching the bigs, veterans like Starlin Castro and Aaron Hicks were achieving new levels of performance, and mercurial pitchers like Michael Pineda and Luis Severino were finding consistency. The only problem was the strangely awful play of their ace Masahiro Tanaka.

Now, of course, everything appears to be crumbling, except for Tanaka. Tanaka has just turned in his best three-start stretch in months, finally flashing the kind of play that made him a legitimate Cy Young contender for much of 2016.

As Ryan mentioned last week, a couple of key differences have helped Tanaka start to turn things around: he's keeping the ball on the ground and out of the outfield bleachers. After seeing a quarter of his fly balls go for home runs over his first 14 starts, Tanaka hasn't allowed a homer across his past three starts, and he's seen his groundball rate rocket from 46% to 61% between those two spans.

The results have obviously been excellent. He's struck out 22 batters in 21 innings, walking just five and posting a 1.29 ERA. Encouragingly, after giving up plenty of hard contact during the first couple months, Tanaka has allowed just a 19.6% hard contact rate over his last three starts, according to FanGraphs. He's also posted a stellar 18.6% swinging strike rate. If opposing hitters can't help themselves but whiff and hit ground balls, Tanaka will be just fine.

How has Tanaka managed this? There could be any number of explanations, random variance possibly chief among them, especially over such a short span. Yet perhaps there is a simple explanation staring us right in the face: Tanaka has been throwing heat these past couple weeks.

Tanaka always has had the ability to throw hard, but in recent years, he's mostly seen his velocity drop, and he often seemingly abandoned his four-seam fastball. From Brooks Baseball, here's Tanaka's average four-seam velocity over his first three years in New York:

Here's the rate at which he's thrown the pitch:

By last season, Tanaka was barely averaging 92 mph, a mediocre level for a righty starter, and he was throwing the four-seamer not even 10% of the time. It's not hard to imagine why Tanaka lost faith in the pitch: between 2014 and 2016, hitters batted .318 and slugged .644 against his four-seamer. He allowed 19 home runs in that span with the four-seamer, more than any other pitch. Most likely, Tanaka looked at his four-seamer's middling velocity and poor results and decided to rely more heavily on the other aspects of his arsenal.

Something's changed recently, however. According to Baseball Savant, Tanaka is sitting at 93.5 mph on his four-seam fastball over his past three starts, compared with 91.2 mph prior to that. At one point, he touched 97 mph. He's thrown the pitch about 17% of the time. Tanaka isn't sitting 91-92 with the pitch and showing reticence to use it. Instead, he appears to be throwing the four-seamer with more conviction.

It's hard to say if the four-seamer itself is performing better at its elevated velocity level. Over those three starts, Tanaka's generated four whiffs on 17 swings against the four-seamer, a good rate for a fastball, but he's also allowed three hits on seven batted balls. Yet those seven batted balls have averaged an exit velocity of just 71 mph. So at the very least, the harder fastball has produced some whiffs and weak contact.

What a good fasbtall could do for Tanaka might have more to do with the rest of his repertoire. Tanaka possesses one of the game's deepest arsenals, equipped with a devastating splitter, a sharp slider, and a slow curve. He's needed those secondaries to be great in the past, to make up for his poor fastball. If Tanaka was suddenly throwing 94 mph consistently, hitters would have another potential weapon to worry about. The fear of a quality fastball could allow the rest of Tanaka's game to play up.

It's a tiny sample, but over these past three starts in which Tanaka has been pumping relative gas, he's yielded a .144 wOBA with his slider, and a wOBA of literally zero with his splitter. Again, it's just three games, but this trio of starts has started to provide evidence that a Tanaka with plus velocity is capable of dominating.

There's no telling if Tanaka can hold plus velocity for the rest of the season. We can’t even be sure that this added heat is what's spurred his recent streak. Yet even if we cannot prove causation, there has certainly been a correlation between Tanaka's velocity spike and his best performances of the year. Intuitively, Tanaka should be a nightmare to face if he's capable of bringing a strong fastball to go along with his crushing breaking pitches. Hopefully, he can keep this up, because a true ace is something the Yankees could use as they try to survive their current rough patch.