In two weeks and one day Masahiro Tanaka will be on the mound for Opening Day at Yankee Stadium. He’ll make his fourth Opening Day start in the last five years thanks to Luis Severino’s shoulder issue. Tanaka’s Opening Day history isn’t good (14 runs in 12.2 innings), but who cares. What happened in 2015-17 has no bearing on 2019.

Anyway, Tanaka has been very good so far during Grapefruit League play, allowing two runs in 6.1 innings. And that is completely meaningless. Example: Tanaka had a career best 0.38 ERA in Spring Training 2017 and a career worst 4.74 ERA during the 2017 regular season. It’s 6.1 innings! Good or bad, his spring performance means nothing.

For a veteran like Tanaka, it’s more instructive to track the process than the results. Sometimes in the spring you can spot a swing change or a delivery tweak. For example, Tanaka employed a little pause at the top of his leg left during his first Grapefruit League start this year. Check it out:

That caught my attention. Tanaka did it a few times during that start and varied the pause. Sometimes it was even a little more exaggerated than that. It didn’t last though. Tanaka was back to his usual smooth, continuous leg motion with no pause in his second Grapefruit League start. Didn’t do it once. Maybe he gave up on the pause. We’ll see.

The pause might be one of those Spring Training nothings. Tanaka’s new curveball is not.  Earlier this spring he said he started toying with a new curveball — a new knuckle curve, specifically — late last year because he didn’t like the traditional curveball he’s been throwing pretty much his entire career, and he’s continuing to work on it this year.

“I really didn’t like how the previous curveball was moving. So I wanted to try something new and that’s where basically I have a new curveball now,” said Tanaka to Mark Didtler through a translator. “It’s something that I’ve been kind of been playing around with or trying during the later part of the season last year. Actually I’ve thrown a couple in a game towards the end of last season. So I kept working on it and working on it.”

Here is the obligatory GIF of Tanaka’s new knucklecurve:

It’s a little snappier than Tanaka’s old curveball, though the big difference is the radar gun. That pitch was 80 mph on the television gun — the YES Network gun has matched Trackman (i.e. Statcast) for years now and is generally very reliable, even in Spring Training — which is awfully hard for a curveball. Last year’s Tanaka’s curve averaged 77.3 mph.

In his five seasons with the Yankees, Tanaka has thrown 17 total curveballs at 80 mph or better, with eight of the 17 coming in 2016. Here are the 2018 league averages:

• Curveballs: 78.3 mph
• Knuckle curves: 80.9 mph

The velocity difference more or less matches Tanaka’s. There’s a three mile-an-hour separation between a curveball and knuckle curve, on average. We haven’t seen many knuckle curves from Tanaka thus far this spring — he said he threw some late last year, but Statcast didn’t pick up any — so we’re definitely short on information right now.

Tanaka typically uses his curveball to steal strikes early in the count. Roughly 7% of the pitches Tanaka has thrown in his MLB career are curveballs, and approximately 62% of his curveballs have been thrown as the first pitch of an at-bat. It’s a clear change of pace/steal a strike pitch. Not a finish pitch or anything like that. It’s a sneak attack pitch.

I don’t see that changing anytime soon, even if Tanaka gives up the traditional curve and goes with the knuckle curve full-time. He’s always going to be a slider/splitter pitcher with a show-me fastball. When you have two offspeed pitches as good as Tanaka’s slider and splitter, there’s no sense in getting cute with your fourth or fifth best pitch.

Maybe the knuckle curve proves to be so effective that Tanaka can use it as a putaway pitch. I’d bet against it. At this point, Tanaka is who he is, and he’s not going to drastically change anything until the hitters tell him it’s necessary, like they told CC Sabathia he needed a cutter. Tanaka is not at that point yet. He’s tinkering more than overhauling.

Tanaka is a master craftsman and he knows how to best use his arsenal. The knuckle curve is a (theoretically) better version of his old curve and gives hitters one more thing to think about, and that’s it. Not something to lean on heavily, you know? For now, the knuckle curve is a #thingtowatch, even if it doesn’t figure to be a real impact pitch going forward.