The player who is most valuable (or maybe better said, the biggest upgrade) over a full season is also the most valuable/biggest upgrade over the final third of a season or in the playoffs. If Manny plays like the 5-7 WAR player that he’s been in the past, that’s a bigger upgrade than any reliever can be, and all but the most elite starters. The only caveat I’ll give is that the value of pitchers goes up maybe 20-30% in the playoffs because the off-days allow the team to use them in a higher percentage of games than in the regular season.