FWIW...PECOTA takes on Roberts vs. DeRosa Roberts 651PA 14HR SB 35/43 (81%) .284/.366/.439 Eq .282/.367/.453 EqA .293 MLVR 0.043 VORP 33.5 WARP 6.6
DeRosa 488PA 12HR SB 3/5 .286/.360/.439 Eq .280/.354/.430 EqA .270 MLVR 0.074 VORP 18.9 WARP 3.5 VORP (offense only in runs) and WARP (Offense + defense in wins) are cumulative stats. Roberts projection is for about 180 more PA. Assuming you "add" the PA missed to DeRosa's WARP you end up around 4.6, making Roberts about 2 wins better. (DeRosa is unlikely to get leadoff hitter amounts of PA, but...) MLVr is a rate stat that looks at runs/g added by that player in an otherwise average lineup. Roberts has an edge here, as well as EqA - an indication of total offensive contribution including baserunning. Add this to the potential use of DeRosa's line in a super-sub role, and ???? How much would the loss of the traded pieces mean to the pitching side? All advantage is off if Pie is traded away (at least by PECOTA prediction). I think we are likely very close to Brewers in the NLC, and a two game swing may be the difference. I'm still not sure how to value a Roberts trade.