Would appreciate the views of good tourney players cos I'm still not sure what the right move is here.
DTD deepstack. Blinds are from memory 1000/2000/100 and we've posted the big blind playing a stack of 55k. Mid position raises to 4500 and is the only player at the table who has me covered - seems a decent player, played quite a few pots but done nothing out of line. Folds around to the button who has been button raising actively and he shoves his short stack of 12,500 in the middle. We have

in the big blind. What is the right move? Do we isolate the early raiser, flat the all in or take a different line?