Here's what matters for a player playing first base
2. Hitting for power
If defense mattered at all, neither Cabrera nor Fielder would be first baseman. They would DH. No one gives a crap. First base is the position you put the least mobile, least athletic guy who's bat is worth having in the lineup. It simply doesn't matter. Most glove glove first baseman can't do crap at third or any other position that requires fielding skill.
Morse has now shown for three seasons that when he's healthy, he mashes. He hits better than Laroche. He has a huge fan following.
1. I love Morse but the problem with this post is the part about staying healthy. If he's not in the in lineup it doesn't matter if he's a better hitter. I have no problem keeping him if you don't get a decent offer.
2. Cabrera and Fielder are at 1B because their bats are insane. Morse's best year is pretty much their average years. You can make that trade off if Morse was going to do that every year. Your position is based on the assumption that Morse can stay healthy and put up numbers comparable to his best year.
3. Defense does matter at 1B. Is it the most important thing? No. But when you have an elite one that can put up good offensive numbers then you can't just throw defense out of the debate.
In a vacuum where you assume the best case scenario, sure Morse is the better hitter. The problem is he hasn't stayed healthy 2 of the past 3 years. No one loves Morse more than me but IMO it would have been a risk to let LaRoche walk completely and assume Morse would be healthy all year. Maybe Moore could have stepped in but that's no guarantee either and for a team that can win it all I think you have to go with the safer option.