let's say rubio gets 10%. he drops, you can split it something like 3/3/4. then, trump gets over 40% and gets a few more delegates. neither cruz nor kasich benefit in any meaningful way, but trump gets more delegates. and, if you carry that trend forward over another 30 states, you're not doing anything but making it easier for him.
michigan was a state that was friendly to kasich. the surprise is that cruz overperformed at the expense of kasich, no doubt because he's pushing this "only i can beat trump" line. what about california? you think the best way to beat trump in california is a moderate, bilingual hispanic or a rino from ohio?
if they really want to beat trump, they need to coast with all three. they have the field dominated. nobody will win, but you keep trump under 40 and get ready for the convention.