The Padres announced Friday that they have signed 31-year-old Adam Warren, lately of Seattle, originally of North Carolina, and most notably of New York, to a one-year, $2 million deal, with a $2.5 million club option (and $500,000 buy-out) for 2020. In San Diego, Warren will join Kirby Yates, Craig Stammen, and Matt Strahm at the head of what should be a reasonably effective relief corps; the Padres’ 3.2 WAR projection is sixth-best in the NL and matches precisely that of division rivals Los Angeles and San Francisco. Warren might also, in the event the somewhat-less-impressive San Diego rotation does not perform at its best, throw a few innings at the beginning of games, either as a traditional starter or as an “opener.”

It is this mostly-theoretical capacity — to pitch relatively effectively both as a spot starter/long reliever and in more traditional relief roles — that has long tantalized the various clubs that have sought Warren out since his debut for the Yankees in 2012, though this appeal has dulled somewhat since a poor turn as a swing-man for the Cubs in the early part of 2016 (his 5.83 FIP during that half-season was his worst mark since 2.1 poor innings in his debut season by more than half a run). The Mariners, for whom Warren pitched from late July of last year to the season’s close, were unique among his three clubs in only using Warren out of the ‘pen, and he rewarded them somewhat poorly by posting his worst performance (4.82 FIP, 1.88 K/BB ratio) since that half-season in Chicago in 21.2 innings of work. He has not started a game since 2016, or more than one game a season since 2015.

It is both facile and also true that Warren was a good reliever for the Yankees, a passable starter for the same club, and a fairly bad pitcher for everyone else:

Adam Warren Has Been Bad Outside New York IP ERA FIP K% BB% wOBA As a Yankees Reliever 300.2 2.90 3.41 23.0% 7.8% .284 As a Yankees Starter 106.1 3.98 4.20 17.1% 7.9% .307 For Everyone Else 56.2 5.08 5.45 17.0% 10.9% .321

The question, then, is whether there’s something about the context in which Warren pitched in New York that has been determinative of his success in that environment, or whether his poor performance out of pinstripes, which came on two separate occasions nearly two years apart, is simply the result of bad luck or other ephemera coinciding with time outside of Gotham. After all, another presentation of the numbers above — equally true — might be to say that Warren has been acceptable as a reliever, regardless of uniform (3.27 ERA, 3.74 FIP, .291 wOBA) and somewhat worse as a starter (3.88 ERA, 4.16 FIP, .303 wOBA). Seen in this light, the facts of Warren’s career to date suggests that San Diego’s apparent plan — to sign Warren as a reliever, at a reliever’s price, and use him as such — is quite reasonable.

The balance of evidence seems to be that Warren has, in the past, responded poorly to the changes in usage and approach that have coincided with changing clubs. Upon his arrival in Chicago in 2016, Warren’s career changeup usage sat at about 15%. During his brief run for the Cubs, his usage of the pitch jumped to 22.1% — then and now the highest mark of his career. Once back in New York after July (as one-quarter of the other end of the Aroldis Chapman trade), his changeup usage dropped back down to and beyond his normal levels and his overall performance trended upwards. When moving from New York to Seattle in the middle of the 2018 season, his pitch mix remained roughly as it had been in 2017 and the early part of 2018 in New York, but the situations in which he was used — as Dan Szymborski suggested they should at the time — became significantly more important; Warren’s average game leverage index (gmLI), which measures the leverage at the time he entered the game, jumped from 0.82 and 0.64 for New York in 2017 and 2018 to 1.05 in Seattle.

With Yates (1.68 gmLI in 2018) and Stamen (1.53) already in house in San Diego, Warren will perhaps be able to slide into the role in which he’s been most effective in the past: as the sixth- and seventh-inning swing-man pitching ahead of more electric relievers who are more than capable of taking later innings and higher-impact moments. Yates and Stamen aren’t Chapman or Dellin Betances, to be sure, but they’re certainly effective enough to take some of the pressure off of Warren. Warren’s mostly-neutral platoon splits (.291 wOBA allowed to lefties versus .296 allowed to righties), meanwhile, will help bring some balance to a San Diego relief corps that allowed a .269 wOBA to righties in 2018 but got lit up to the tune of .318 by lefties.

Warren can clearly be a highly effective reliever, and the Padres are wise to have acquired him as one. With Manny Machado in the lineup and a 78-84 projection that suggests that each marginal win for San Diego in 2019 will be of tremendous value, this is exactly the kind of move you’d like to see the Padres make. They will perhaps be best served, however, by resisting the temptation to make of their new reliever something more than what he is already. Two times does not a pattern make, but the circumstantial evidence of reduced success in the face of change, in combination with the value Warren clearly assigns to comfort and familiarity, suggests that the best policy for San Diego’s coaches will be to leave their new reliever well enough alone.