For those who watch the Yankees every day, what is the consensus on his ability to play third base? I was ready to jump in here and argue that a small market team should be willing to absorb far more than 5 million per year since Sandoval was also a 12% better than league average hitter at third base in his most recent season and just got 20 million per year (buyout included) while being about a decade younger and having better defensive ability, accounting for some of the gap between them. I was having a hard time seeing a 45 million dollar difference between them over the next three seasons until I considered the possibility that ARod has to move to first base because his his hips and age. At that point, hitting around 10% better than league average (assuming some decline) makes James Loney the closest comp from last year's hitters and he was valued at about 5 million by fangraphs.
If ARod can play slightly below average defense at third and still hit at something near that 112 OPS+ for the next three seasons, he'd be one of the best bargains in baseball at 5 million per. If he's a first baseman with average or below average defense in that span, he's probably worth about that much. If he's a below average defensive first baseman, or worse, a DH... or even worse, incapable of reaching that level of hitting at all, he could end up a sunk cost. Might be worth the risk for a small market team with a hole in their lineup and a belief that they are one or two average bats away from the playoffs, but that might be a tougher sell for the Yankees to make to another GM than you are suggesting, Plympton.
Your post did lead me to completely reversing my thinking from reaction to posting, though, so thanks for provoking some thought.