I know all the arguments in favor of Morris - winningest pitcher of the 80s, clutch postseason performances, mystical ability to "pitch to the score" (since disproven here). I know my arguments against Morris - 3.90 career ERA, 186 career losses, no single season with an ERA below 3.00 despite fashioning a career in a pitcher-friendly era. There are a lot of pitchers like Morris in his era; they just weren't lucky enough to play for a team that handed him the ball in Game 7 of a World Series.
The amazing Joe Posnanski is not a believer in Morris's candidacy either. (He also supports Dan Quisenberry for the Hall of Fame, but that's a crusade for another day.) Posnanski has written about this before, but takes a different tactic here by comparing Morris to another one of his contemporaries - Dennis Martinez:
He is an interesting case to me because he is the first big league player from Nicaragua, he spread out his success over a very long career and, yes, when you add it all up he has a very similar case to Jack Morris, who is gaining Hall of Fame momentum.
Morris: 254-186, 3.90 ERA, 2,478 Ks, 1,390 walks, 1.296 WHIP, 28 shutouts, 105 ERA+.
Martinez: 245-193, 3.70 ERA, 2,149 Ks, 1,165 walks, 1.266 WHIP, 30 shutouts, 106 ERA+.
Morris pitched one of the great World Series games ever.
Martinez is one of 16 players since 1900 to have thrown a perfect game.
Morris led the league in wins twice, complete games once.
Martinez led the league in wins once, complete games twice, innings pitched once, shutouts once and ERA once.
Morris won 20 games three times and was selected to five All-Star Games.
Martinez never won 20, but he had three good years shortened by strikes and he was selected to four All-Star Games. And from age 32-40, he had a 129 ERA+ — Morris only once in his career managed a single season with an ERA of 129 or better.