Now, now, let's wait a second here.
Kingpin is NOT some "fat guy". His...mmm...girth, is actually ALL MUSCLE. I believe he's in a strength class similar to or above Captain America (CL 1/2). Additionally, he's a martial arts master - he mastered judo, jiu-jitsu and sumo. He's deceptively fast, and he's actually been able to hang with Spider-Man for awhile, and he's beaten Daredevil in the past.
Of course, I don't know anything about Blockbuster, so maybe that's still not enough to win. But don't sell Kingpin short - he's one of the better H2H fighters in Marvel.