When the Mariners traded for Jack Wilson, we knew it a move fueled by defense. The front office and coaching staff made no secret of that. Wilson brought a glove, an excellent glove capable of making up for a lackluster bat, and this was okay, because we knew that he'd be able to field while remaining something above a black hole at the plate.

However, over the span of the next six weeks, Wilson would collect 116 plate appearances as a Mariner, and over those 116 plate appearances, he would hit just .224 with a .562 OPS. While no one expected Wilson to light it up, this was beyond terrible. This was a Ronny Cedeno level of bad, and in part because the whole Cedeno experience was still fresh in our minds, there developed this sentiment that Wilson's an "NL hitter," that he's a guy who can sort of hold his own on the other side but who becomes completely overmatched against the superior AL competition. Cedeno was awful here and successful with Pittsburgh. Wilson, some people have claimed, is a player in the same kind of mold.

I find this claim to be dubious for three reasons:

(1) There's no such thing as an "AL hitter" or an "NL hitter." While the AL is the better league and has the better pitchers overall, it's not so lopsided that NL hitters come over and lose tons of points off their production. I identified 42 hitters who switched leagues either last offseason or during the year and who accumulated at least 100 PAs on both sides. Those 42 players averaged a .315 wOBA in the AL (not park-adjusted) and a .323 wOBA in the NL. Over a full season, that's a difference of about four runs. It seems significant, but it's not colossal. Jack Wilson may have struggled over here, but what about, I dunno, Jeremy Reed? What about Endy Chavez or Alex Cora? It's not an idea that makes a lot of sense when you think about it, and it's not an idea that holds up to much scrutiny.

(2) Jack Wilson has collected 470 PAs during interleague play over his career. In those 470 PAs, he's hit .301/.334/.420, and he's been good in each of the last three seasons.

(3) 116 plate appearances. That's all we saw from Wilson in the AL, and for many of them he was playing hurt. 116 plate appearances barely tell you anything. If Wilson had come over and sucked that bad for a whole year, that would be one thing. But he sucked for a handful of weeks. A 3/4/5 weighting of his most recent seasons yields an un-adjusted wOBA of .301, which isn't that bad for a defense-first shortstop.

Jack Wilson may be a baseball player in the National League style, but there's no good reason to believe that his bat will continue to be this bad as long as he plays for an AL team. There is an AL adjustment that docks him a few points, but what we saw from him was extreme, a performance towards the lower bound of his probability distribution. It isn't realistic to expect him to keep that up. He's proven over the years that, while he's not a great hitter, or a good one, or an average one, he's a below-average one, and not a disaster. That's the player we traded for, and that's the player we almost certainly still have.

How Seattle will affect Wilson's offense is, of course, a legitimate question. Not only did he switch leagues, but he also moved to a park that doesn't treat righties very kindly. That's going to be an adjustment. However, for one thing, Wilson's power, like Jose Lopez's, is down the line to left, so he won't get killed by that power alley, and for another, the bulk of Wilson's production comes from line drives instead of fly balls anyway, so Safeco shouldn't hurt him as bad as it has guys like Mike Cameron. Wilson sprays singles. A single is a single in any ballpark.

Jack Wilson isn't a sexy, impact type of player, and at 32 this December, he's not on the way up. However, as a regular shortstop who can turn a lot of balls into outs and make a lot of low-to-the-ground contact, we could do a lot worse. Assuming his offense hasn't completely collapsed and that he's something like a +10 defender, we should see him end up in the neighborhood of a 1.5 - 2.0 WAR, and that's going to help. That's going to help quite a bit.