DPM - that is too much aggregation to be a meaningful way of comparing the options. Tavares would drag down any grouping in terms of any stat except SBs.
How much of a better hitter was Dye than Willie vs. RHP last year?
373 PAs, .236 / .323 / .434, 20 Hr, .332 wOBA.
Willie was .040 better in OBP at the expense of .020 in SLG. The home runs look pretty, but Willie's 2b (15) and 3B (6) almost completely make up the power difference (Dye's 12 and 1). I'll go further and say that taking Dye out of the Cell (or whatever they call it now) would likely depress his homers, too, so I don't think his SLG advantage would hold up. In fairness, his '08 splits were terrific, but '07 stunk, too.
All of this is without discussing defense. Dye is Dunn's chief competitor for worst outfielder the past 5 years, at least by UZR. A 20 run difference between Harris and Dye on defense would be in line with what most Fans project.
I just do not see Dye playing ahead of Willie against RHP, which is what you see most of the time.
Harris v RHP; LHP
2009 (348 PA) .248/.365/.414, 7 HR, .347 wOBA; ( 45 PA) .121/.356/.212, 0 HR, .293 wOBA
2008 (311 PA) .255/.351/.404, 8 HR, .334 wOBA; (113 PA) .240/.327/.450, 5 HR, .341 wOBA
2007 (335 PA) .283/.358/.418, 2 HR, .342 wOBA; ( 56 PA) .191/.291/.234, 0 HR, .250 wOBA
Against LHP, his time would come at the expense of Morse or J-Max. I'm not going to argue he is not still a great hitter against LHP. Conceivably, if you were to send Desmond down or release Guzman, there may be room on the roster for about 200 AB on the short side of a RF platoon, 1B backup (he says he's willing), and PH in the NL. That's figuring Bruntlett as your MI backup, 3 backup OFs (Dye, Morse, and a CF), and using Harris, Morse, and Dye in the infield as needed.