Hi All. Lurker for years, figured I'd just jump in.
Wondering Fishercat, what does "rebound" look like? Are we talking about a full season of his first-half play, or something greater than that? I'm a bit concerned that even the 2nd half numbers weren't the floor here. I assume we're talking about a player here who has peaked physically, no?
So, taking from the small sample above, I'll also add in their ages in their rookie year and add in Yoshida
Ichiro Suzuki (-.020 OPS from 1H to 2H -.020 OPS from Y1 to Y2) (he was also ROY and MVP...) - 27 years old
Hideki Matsui (-.040 OPS from 1H to 2H +.125 OPS from Y1 to Y2) - 29 years old
Nori Aoki (-.050 OPS from 1H to 2H, -.060 OPS from Y1 to Y2) - 30 years old
Kaz Matsui (-.080 OPS from 1H to 2H; -.070 OPS from Y1 to Y2) - 28 years old
Kosuke Fukudome (-.150 OPS from 1H to 2H; +.060 OPS from Y1 to Y2 - 31 years old
Seiya Suzuki (-.070 OPS from 1H to 2H, +.060 OPS from Y1 to Y2) - 27 years old
Masataka Yoshida (-.210 OPS from 1H to 2H, ??? from Y1 to Y2) - 29 years old.
I think the bigger mitigating factor may be the degree of the drop in 2023 over age. Hideki Matsui and Kosuke Fukudome were both of similar age or older and made major, value-added gains in Year 2 - even considering Fukudome's big second half drop off in Y1. With this very small sample, I don't see an age trend to be honest - most of these guys whose stories are done were at least useful major leaguers for about the length of Yoshida's deal.
The bigger concern may be the degree of the drop. Only Kosuke Fukudome lost more than .1 OPS from first to second half and no one had as hard a drop as Yoshida did. We have no data for a first year Japanese hitter (that I'm aware of) who fell off as hard as Yoshida did and what year two might look like. Like, you hope it's Hideki Matsui. Yoshida and Matsui, over the course of the full season, has strikingly similar slash lines playing LF.
Yoshida: 289-338-445 (109 OPS+)
Matsui: 287-353-435 (109 OPS+)
The "dream" rebound is something like Hideki Matsui's Y2 (298-390-522) or Masataka Yoshida 1H (316-382-492) where he isn't fatigued, adjusts to year two, and puts up a 3-5 WAR type season even if you hate his defense. A 3 WAR corner OF is well worth the contract he has and even if that's his ceiling, if he can rebound to that or even a bit worse, we're happy. Now, the issue is that Masui was an absolute monster in the JPCL In his day - huge power numbers Yoshida never touched, and that made his offensive upside there higher. But Yoshida is no slouch
The nightmare scenario is that his bad stuff gets worse (defense goes from ugly to unplayable, he's permanently lost the strike zone, MLB pitching figured out his weaknesses and he can't fix it or respond to it adequately) and that precipitous 2nd half drop is more than just fatigue and adjustments. That could snowball real quickly if so and the Sox could have a moderate sized albatross on their hands. At that point, this suddenly becomes a much harder contract to move.
If you made me guess, I don't think the defense gets much better, so if that's bad now it just gets worse. I do think the BB/K gets better - his eye was way too good in Japan for that second half 7 BB to 45 K ratio to be anywhere near real. I think his rebound falls close to the first half than second half, maybe something like a 290-350-450 kind of line which I think is alright if not ideal. But that's a relatively uneducated guess. I personally wouldn't be surprised if he was hurt for some of this either but again, I got little to show for that.