Due to the glut of outfielders available on the free agent market and the qualifying offer attached to him, Dexter Fowler sits unsigned. The White Sox, despite the glut of outfielders available and their need to find an upgrade over Avisail Garcia, have signed no outfielders. Thus, there is plenty of speculation on whom the White Sox are targeting. Fowler is the most common mention.
After spending most of his career with the Rockies, Fowler was traded before the 2014 season to the Astros and traded again before last season to the Cubs. Through it all, he's kept his contributions at the plate fairly consistent. He has had an above-average wRC+ every year since 2011. His walk rate and strikeout rate are pretty steady; his walk rate in particular keeps his offensive floor at a decent level. His batted ball distribution, which includes a good number of line drives and few popups, helps his BABIP stay fairly high. His speed is good as well, but for a speedy guy he does not hit too many grounders.
All that to say that he is likely to stay a good offensive player entering his age-30 season.
Should Fowler sign with the White Sox, he could play left field or right field since Adam Eaton has center field on lockdown. Melky Cabrera is in left field, and Avisail Garcia is in right field. There is no lockdown occurring there. The steel door is wide open. I'll let South Side Sox sum up the cost/benefit analysis of each option:
Basically, moving Fowler from center field to right field minimizes his biggest asset, his speed, while emphasizing his arm, a consistent problem. Bad jumps, reads, and routes, his biggest problem, won't be fixed at all by the move to right.
A move to left field is another option for Fowler It helps to lessen the impact of Fowler's arm, but then you have to find a new place for Melky Cabrera. Right field for Melky is another bad idea. DH would work, but then Adam LaRoche is left on the bench and you still need a right fielder. In other words, we have a whole new can of worms to deal with.
It doesn't sound like he's that great an option, but the point of this article is not to determine if his signing is a good idea but to look at his potential effect on the roster. Let's use some projections and speculation to see how Fowler fits.
Steamer puts Fowler at 1.6 fWAR. As best I can tell, ZiPS has Fowler at 2.4 WAR. Average them together, and you get an average center fielder. However, in this scenario, Fowler will not be playing center field. He'll be playing either left or right field. Moving down the defensive spectrum means his positional adjustment changes. According to FanGraphs, left field and right field have a full 10-run difference in positional adjustment, from +2.5 to -7.5.
Therefore, it's a reasonable thing to say, I think, that in order to maintain his status as an average player, Fowler must be at least 10 runs better on defense in a corner than in center field. Fowler has no history in a corner outfield spot in the majors except for 1 inning in 2008, so that's a reminder that we're in conjecture here. Averaging together Fowler's previous three years of defensive values, and he's roughly a -11.7 DRS and -8.5 UZR fielder in center. In order to achieve a similar WAR value of 2, Fowler must then be something like an average defender in either corner (offensive expectations are increased in the corners, so his bat has less value).
Looking over the past three years with a minimum of 1000 innings played, average-ish right fielders include Will Venable, new Royal Travis Snider, Brandon Moss, and Jose Bautista. Fowler can't be any worse than those guys, right? Venable doesn't have much of an arm either, and Bautista seriously lacks range. Guys like Curtis Granderson, Bryce Harper, and Josh Reddick have succeeded in right field despite lower arm ratings.
Doing the same for left fielders, one finds names like Matt Joyce, Nate McLouth, and Robbie Grossman around the average range. Again, Fowler can't be worse than those guys, right?
I suppose this is a long way of saying that it's reasonable for Fowler to maintain his status as an average player and be potentially above average if his BABIP swings in 2016.
The FanGraphs projected depth charts have 0.9 WAR in left field and 0.3 WAR in right field. Fowler, despite any warts, would be roughly a two-win upgrade in either spot, assuming Melky moves to right field if Fowler mans left field.
Those same projected depth charts have the Royals and White Sox in almost a dead heat in total WAR, meaning that on true talent, the teams are very similar. The Royals have superior position players, but the Sox have Chris Sale, Jose Quintana, and Carlos Rodon in the rotation to support a pitching staff that projects better than the Royals'. In the world of projections, Fowler brings the White Sox above the Royals in terms of expected performance.
Let's take a step back, though. Last year, the White Sox finished at 76-86, while the Royals finished at 95-67 and won the World Series. The Sox had literally the worst group of position players as measured by fWAR. There was a large gap to be made up.
This offseason, the Sox have been working hard to make up that gap. They brought in Todd Frazier to fill their third base black hole, and Brett Lawrie will be at second base. Lawrie may be a little exposed at second in terms of defense, but his bat will play there. Both players will bring positive values to positions that were big negatives last year. Alex Avila and Dioner Navarro will be upgrades at catcher over Tyler Flowers and Geovany Soto, though the difference isn't as large as at third and second. Adam LaRoche's performance at DH cratered last year; he is not likely to be as bad this year.
In other words, the Sox have significantly upgraded a good portion of their roster, and the addition of Dexter Fowler would continue that process. He would bring the Sox above the Royals in terms of projections, and he would help close the gap in the standings. He helps make the Sox a challenger in the AL Central.