Is This bad MTT poker?

[pologuy64]

This situation comes up alot. this is a play that i like to do but sumtimes i get caught(works about 3.5 out of 5 times)
if im in late middle position or late position. late in tourneys and i finding myself below avg. but not always done(5k avg. being 8k) wit big blinds and its folded around to me. at times i will risk 3/4 to all my chips wit any two cards to steal the blinds. note that the blind are always high and there r atnes in the middle also. Should i use this play to steal? if not how do i reframe from just blinding all my chips away if im card dead?