Hyun-Jin Ryu is back and is succeeding with his mysterious fastball

The Dodgers got an encouraging start from Hyun-Jin Ryu last night against the Giants. After missing 3 1/2 months with a “strained” groin, he came back and looked like he hadn’t missed a beat.

For all the hand-wringing folks did at the trade deadline — some deserved, some not — getting Ryu back this month is like adding a mid-rotation starter for the stretch run. His return has allowed the Dodgers to move Kenta Maeda and Ross Stripling to the bullpen, even if Maeda’s first outing didn’t go as planned and Stripling is currently on the disabled list.

Not only is Ryu coming back like the Dodgers getting a mid-rotation starter at the trade deadline, he might be their best pitcher. OK, maybe not, but my goodness, he has been something else this season.

Since his first start of the season when he allowed three runs in 3 2/3 innings, he has allowed four runs. Total. Sure, it has only been 32 innings, but he has more scoreless outings (4) than outings in which he allowed runs (3). His command/control is solid and he’s missing more bats than he ever has in his career (30.9 K%). In fact, his fastball — despite averaging just 91.2 MPH this season, according to Brooks Baseball — has a 14.6 percent whiff rate, almost double from his previous career best of 7.8 percent. What’s funny is the fact he’s only throwing it (4- and 2-seamer) 39.1 percent of the time. If he threw it more, the whiff rate might decline, but it just shows that even in limited exposure, it has been a great pitch for him.

Of his 15 strikeouts, 13 have been swinging and it isn’t like he’s getting guys to chase it outside the zone.

It’s mysterious. He doesn’t have a high spin-rate fastball, either. The MLB average spin rate on a 4-seam fastball is 2,262 MPH. Ryu’s 4-seamer (since 2-seamers and sinkers don’t spin nearly as much) is averaging 2,071 RPM, which is just slightly more than his 2-seamer/sinker (2,054 RPM). His average spin rate is the 31st-lowest of any pitcher in baseball. He’s in the same company as guys like Cole Hamels (2,069 RPM), Michael Wacha (2,070) and Amir Garrett (2,072).

Ryu doesn’t throw it as much as these guys. He also doesn’t throw it as hard as Wacha and Garrett (who is a reliever, I might add). Yet, it’s still far and away the best of the quartet, despite having logged just 35 2/3 innings this season. Those other guys succeed with their other pitches (not that Ryu’s secondaries are bad), but it just makes it all the more impressive that Ryu is able to be that successful with his fastball while the other three haven’t been.

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This is something to monitor for the remainder of the season, but if he’s able to maintain this kind of production — especially with his fastball — then Ryu might find himself starting a postseason game for the first time since 2014. You know, should the Dodgers make it.