It seems that each time Masahiro Tanaka settles a question about himself, another one replaces it.
First, it was whether or not his tremendous performance in Japan would translate to MLB. It did. Then, speculation centered on the partial tear of his ulnar collateral ligament and when it would pop. It hasn't. Next, would Tanaka opt out of his contract? Nope.
Coming off arguably his best season in pinstripes in 2016, Tanaka hit a sizable wall at the outset of the 2017 season. All pitchers throw a clunker now and again, but Tanaka got tattooed more often than not in the season's first half.
In 102 first-half innings, Tanaka pitched to a 5.47 ERA, 1.37 WHIP, .276 BAA, .841 OPS with a 2.4 BB/9, 9.1 K/9 and 23 home runs allowed (2.0 HR/9). Besides the strikeout rate, these stats were well below the career rates that Tanaka entered the season touting. Whenever Tanaka showed glimpses of snapping out of the skid, he would fall back.
Tanaka returned from the All-Star break visibly sharper and slowly began to erase the poor results from the first half. In 76 1/3 second-half innings, Tanaka registered a 3.77 ERA, 1.06 WHIP, .230 BAA, .673 OPS with a 1.7 BB/9, 10.7 K/9 and 12 home runs allowed (1.4 HR/9). Every area improved and Tanaka was dominant in the postseason (20 IP, 2 ER, 0 HR, 18 K).
So, the latest question, is whether Tanaka's performance in 2018 will resemble that of the first half or his second half/postseason.
Tanaka was so bad and because the poor stretch extended through the first half last season, it's difficult to simply push it aside. Also, while 29 is not exactly old, it is at the outer edge of what is considered "prime" for a starting pitcher.
On the positive side, Tanaka's first half was the outlier of his four seasons with the Yankees. So, it may be reasonable to suggest that he hit a severe rut and once he figured out his issues he regained his form. Tanaka's success and failure can be mostly attributed to having a good feel for his pitches.
Tanaka threw six types of pitches according to Baseball Savant in 2017. He utilized his slider more often than his signature split-finger fastball in 2017. Tanaka's third most used pitch was classified as a sinker and he threw a four-seam fastball, curve and cutter as well. Of the pitches, Tanaka's slider, split-finger and curve all held batters to under batting averages under .225. The other three pitches were hit hard for averages ranging from .345 to .353.
Tanaka is not going to overpower batters and since the mix of pitches is entirely reliant on movement and location, he has to be completely on his game to generate a strong performance. Tanaka's ability to throw six pitches allows him to determine which offerings are the strongest, however he tends to have a hard time determining when to move away from a certain pitch in-game before it is too late.
This could be the issue with the number of home runs he allowed in 2017. The interesting aspect here is that Tanaka had trouble with the splitter, slider, and sinker (his best pitches) in 2017 when leaving them up in the zone, allowing 29 combined home runs on the pitches, whereas he allowed just 17 on those pitches in 2016. Tanaka must remain down in the zone and establish control early in a game in order to get batters to begin chasing the splitter, sinker and slider.
Tanaka registered the highest strikeout rate of his MLB career in 2017, which should lead us to believe that even in games in which he allowed an abundance of runs, he had good stuff. Another positive development was Tanaka's ground ball rate increased to 49.2 percent, the highest since becoming a Yankee.
When determining expectations for 2018 for Tanaka, they begin with whether or not we believe Tanaka can reduce the number of home runs allowed back to his career line preceding last season (1.1). If he can do so, while remaining stingy when the ball stays in the yard, Tanaka can bring his ERA back below league average.
I'm fairly confident that Tanaka is closer to the pitcher he was in the second half of last season. However, I'm not convinced he can return all the way back to his production in 2016. My concern comes from the fluctuation of the effectiveness of his pitches, which cannot be presumed to improve across the board.
If Tanaka can make 30 starts in 2018 (it would be the third straight season he manages the feat), we can figure on 185-190 innings of work. With that in mind, I'll project Tanaka will turn in a 3.60 ERA, 1.10 WHIP, 1.8 BB/9, 9.2 K/9, 49 GB% and 1.2 HR/9. The reduction in walks and home runs along a bevy of ground balls and a strong strikeout rate should result in better run prevention.
The production might not be flashy or worthy of Cy Young consideration, but they will be more than enough for a Yankees squad that should score a good deal of runs.