coach told him to "block" the base‏

[mbyron]

In general, MC is of course a judgment call. I can envision a play where a little runner (remember, these kids are 11U) bounces off a chunky F5 who is firmly planted. Hard to call MC there.

OTOH, I can envision a play (which sounds like the OP) where F5 goes and gets the runner and knocks him on his butt. I'm all for instructional umpiring up to a certain level, but even 11U kids know that's not baseball.

Whether his coach goes too depends on the first words out of his mouth. If it's "Bobby, what the heck are you doing?" he might stay; if it's "Attaboy, Bobby!" buh-bye.