According to BrooksBaseball.com, Masahiro Tanaka’s repertoire can be classified into six pitches. We all know about his splitter, the best of its kind in the game. His slider is somewhat less recognized but equally effective, boasting a whiff rate of 15.6% in 2018. After that, things don’t look as good.

Tanaka’s four-seam fastball has long been his Achilles’ heel due to its merely average velocity and lack of rise; hitters slugged .594 off it while only whiffing 6.50% of the time in 2018. His cutter hasn’t fared much better, yielding more whiffs (11.63% whiff rate) but even harder contact (.852 opponent slugging percentage). Filling out the righty’s arsenal are his rarely-thrown sinker and curveball. When they were thrown, they were battered, as hitters recorded slugging percentages of .852 and .900 against last year, respectively. It’s weird to say this about a pitcher with six pitches in his arsenal, but Tanaka could really use a good third pitch.

That’s why I fell out of my chair when multiple reports from Japanese media emerged that Tanaka was experimenting with a new pitch in his Sunday spring training start against the Tigers. When the Japanese hurler was asked about the added velocity observed in his curveball - it averaged 77.2 MPH last year, but topped out at 80 MPH on Sunday - Tanaka answered that he was toying with a knuckle-curve, which is what the faster curves were.

Was Tanaka really throwing a new curve, or was he blowing smoke? Let’s look at some footage from Sunday to figure it out for ourselves. First, a look at Tanaka’s old, normal curve:

It’s a fairly nondescript curve - not too slow, not too fast, with noticeable vertical movement but nothing worthy of terms like “lollipop” or “hammer.” It’s perfectly adequate for using as a get-me-over pitch to a lefty for strike one, as Tanaka did above, but it probably can’t be relied on too much beyond that.

Now, let’s turn our attention to Tanaka’s alleged “knuckle-curves.” The Japanese media noted two examples of the pitch. Here is the first of them, a 2-2 pitch to John Hicks which induced an inning-ending pop-up.

Forget the fact that Tanaka missed his spot pretty badly on this offering for a moment. Notice the 80 MPH velocity reading on the pitch in the top left corner, which is substantially faster than his usual bender. Watch the trajectory of the ball. Doesn’t it seem like the break is later and sharper on this one than the previous GIF? Perhaps a better located pitch will prove more conclusive. To that end, I give you exhibit B of Tanaka’s new curveball, which features a split-second cameo of Joe West in the best shape of his life.

This is a perfect two-strike offering, a breaking ball on the lower outside corner which Ronny Rodriguez rolls over to third base. Again, the movement on this pitch seems delayed and sudden compared to Tanaka’s old curve. His normal, get-me-over curveball traveled to the catcher’s mitt in a smooth arc. Comparatively, his new knuckle-curve seems to drop down more drastically at its end, like a graph depicting the law of diminishing returns but with a reversed x-axis.

Of course, one can quibble with Tanaka’s terminology. “Knuckle-curve” is usually reserved for curveballs with slower velocity and more majestic arcs than usual; Dellin Betances’ butterfly bender comes to mind as a prime example. However, there are examples of harder, firmer breaking balls called knuckle-curves. One example is the pitch that Lance McCullers Jr. made his name with (coincidentally, it’s his version that appears in MLB.com’s page for the knuckle-curve). Perhaps Tanaka was trying to emulate McCullers Jr.’s signature pitch, in which case his usage of the term “knuckle-curve” would be justified.

Regardless of the name of the pitch, it’s pretty clear that it is distinct from Tanaka’s old curveball. From considerations of time and space, I will save the possible effects of adding a new curveball to Tanaka’s arsenal for a follow-up piece. For now, let’s just say that Tanaka is working on a new weapon. If he can continue to hone its movement and velocity while locating it as well as he did against Ronny Rodriguez, it will become a weapon indeed. At the very least, it’s something to look forward to in Tanaka’s next spring start.