Can Alexis Díaz repeat his excellent year for the Cincinnati Reds in 2023?

It’s become a bit no more funny business to write about the Seattle Mariners around these parts after the transactions of the last calendar year, but if you’ll briefly indulge me, I’m going to do it again.

Paul Sewald! Surely you didn’t know I was going to lecture you about Paul Sewald this morning, but here we are. The 32 year old former New York Mets draftee entered the 2022 season with a career 4.75 ERA across five seasons of work, though his 3.75 FIP in that time indicated he’d been a bit unlucky in his efforts. That all changed this past season, however, as his luck turned completely, leading to a stellar 2.67 ERA in 64.0 IP of relief - an output that belied the 3.88 FIP he posted.

There were 144 pitchers who tossed at least 50 innings of relief at the MLB level during the 2022 season, and none owned a lower BABIP on his offerings than Sewald (a preposterously low .158). It’s that which brought me here today.

Ranking second on that BABIP leaderboard was Cincinnati Reds uberarm Alexis Díaz, whose .178 was still preposterously low - for reference, only four of the 144 pitchers on the list had a BABIP below even .221. That’s the kind of red flag that usually screams regression, though there are at least a few ways around the previously agreed-upon ‘luck’ factor that is the normalization of balls in play that end up going for hits.

Not all BABIP is created equal, after all. A ball in play off the bat at 118 mph is, for instance, a lot harder to turn into an out in most circumstances than a ball off the bat at 68 mph, the latter needing perfect placement avoiding defenders to have any real chance of becoming a hit. Fly balls, grounders, and liners all factor into the probability of balls in play becoming outs, too, and that’s what brings me back to the Sewald/Díaz pairing atop the low-BABIP rankings.

When you sort that 144 pitcher sample by their batted ball data, Sewald’s story begins to get a few more subplots. By FanGraphs’ definition of soft-contact rate, 26.2% of contact made off his offerings was considered ‘soft,’ the second highest rate among the entire group. On top of that, Sewald seemed to lean into the heavy, moist air of his home park in the Pacific Northwest, as his 51.0% fly-ball rate ranked as the 7th highest among the 144. In other words, the dude became an expert at inducing softly-hit fly-balls, which are the single easiest batted-ball outcome to turn into an out.

You get a lot of those and your BABIP allowed should be absurdly low. Not .158 low, by any means, but near the top of the league’s leaders low. So, while it would be totally logical to expect a mirror-image outing from Sewald in 2023 to feature a BABIP that regresses closer to the league-average of .289, a similar batted-ball profile would still see him land significantly lower than that barring an absurd level of baked-in luck.

Luck, something we’ve not seen a ton of around Reds Country in recent years. Part of me - and that’s admittedly why we’re here - is worried that Díaz just benefitted from a lot of luck during a season in which it didn’t even matter on the larger scale.

At just 17.9%, Díaz’s soft-contact rate checked in at just 67th on the list, and while that’s not a concrete predictor of future performance, that is enough for us to retroactively say he didn’t benefit from a ton of weak contact in 2022. In an even more odd twist, Díaz actually checked in with a higher fly-ball rate than Sewald did in 2022, his 54.5% the 4th highest among the 144 pitchers on whom we’re focused here. Consequently, his 30.3% ground-ball rate checked in as the ninth lowest from that sample, completing the quadrapod of stats that make me say ‘ahh, damnit’ as I begin to look forward to next season.

Soft contact? Not really. Lot of fly balls despite playing home games at GABP? Yep. Not that many grounders? Nope. BABIP that now looks wholly unsustainable? Ahh, damnit.

I’m not about to discount just how brilliant Díaz was for the beleaguered Reds bullpen during the 2022 season. I know it’s not how any of this works, but it sure feels like the 62-100 record could have been a half-dozen losses worse had he not been the lone bright spot in relief. Still, I’ve got some qualms about expecting him to replicate his success in 2023 if he depends on the same mix and approach that got him those results in 2022, since they just don’t look sustainable upon further investigation. Maybe he’ll add a third pitch! Maybe he’ll hammer the bottom of the zone with the slider more often! Maybe he’ll cut down on that walk rate so that even if the rest regresses, he’s never pitching with men on base!

It’s just that it may not be the best idea to just hope it works out as well next year as it did in this one.