I mentioned this in passing elsewhere, so I'd though I'd expand on this.
Value = Offense + Defense + Baserunning
"Value" is my term for a player's total contribution to the team. This includes offense, defense, baserunning, etc. Baserunning compared to the other two categories is fairly insignificant, depending on the player involved. But it's still a part of the total package.
How important is defense compared to offense? It depends on the player. For example, Casey Blake received 5.2 batting Win Shares, and 4.0 fielding Win Shares. Adam Dunn had 28.5 batting and only 1.8 fielding Win Shares. Dunn is the worse fielder, but the better player. Do you see where I'm going?
In a perfect world, you'd have a player with both offensive and defensive skills. In the Indians' case, they have Casey Blake and Jason Dubois. Blake has shown himself to be a good outfielder but a suspect hitter, while Dubois has been scouted as a poor fielder but a promising power hitter.
The problem with Dubois is this: he hasn't proven that he can hit major-league pitching. His strikeout rates in the minors are very high, and his limited at-bats in the majors haven't been encouraging. He's 27, so this isn't an age-related problem.
What does PECOTA say about Dubois? Jason's 2006 weighted mean is 1.9 WARP. Casey Blake's weighted mean is 2.6 WARP. Not that much of a difference, but in close cases I lean towards the guy with the better defense.
Now the Indians should absolutely be looking for better options than Blake: a 2.6 WARP right fielder is probably going to rank near the bottom in the AL. But is Jason Dubois a better option? No.