By advanced metrics, Tanaka is more or less the same pitcher he's been over the past two seasons. His traditional stats, however, tell a vastly different story.
| Season | Win-Loss Record | ERA |
|---|---|---|
| 2015 | 12-7 | 3.51 |
| 2016 | 14-4 | 3.07 |
| 2017 | 7-8 | 5.47 |
Tanaka's ERA has ballooned to 5.47 this year despite the fact he owns a 23.2% strikeout rate, his best mark since his rookie season in 2014, and a career-best 14.7% swinging-strike rate. That swinging-strike rate sits fourth among qualified starters, and it tells us his 23.2% strikeout rate should actually be a touch higher.
Tanaka's 3.86 SIERA is a career-worst mark, but it still ranks 17th among starters. His walk rate (6.1%) is better than the league average (8.6%), and across the board his batted-ball numbers are right in line with his career marks.
So why have things gone south? Tanaka is getting roasted by the long ball.
His home-run-per-fly-ball rate is an inflated 22.5%, and nothing about his batted-ball profile says he should be allowing so many taters.
| Season | Hard-Hit Rate | Soft-Hit Rate | Fly-Ball Rate | HR/FB |
|---|---|---|---|---|
| 2017 | 32.1% | 18.8% | 33.4% | 22.1% |
| Career Average | 32.6% | 18.5% | 31.7% | 15.7% |
If the home-run-per-fly-ball rate starts regressing to his career norms, Tanaka should begin producing useful fantasy numbers, something he hasn't done so far in 2017 as he's 89th among starting pitchers in ESPN's Player Rater.