This kind of discussion always reminds of the Doyle Alexander-John Smoltz trade (and the Sabathia trade for MKE, of course). Haha, Tigers, you gave up a hall of famer for a 35-year-old pitcher. But, Alexander went 9-0 down the stretch in 1987 and got them into the playoffs, where they lost to the Twins. They held off Toronto by two games, and Alexander got the win against Toronto in the first game of the final series, where Detroit caught the Jays.
Was that a bad trade for the Tigers? I'm sure it felt pretty good during that season. At some point, you have to give the front office some grace, and not re-litigate every trade 10 years down the road. I think all of the WAR computation for the various trades can get silly. Do you want an 8-WAR player this season, or a guy who gives you one WAR for 9 years so you can say you won the trade?