[Xenod]

143 is a pretty small sample size and the change in your placement distribution could just be a matter of variance.

You could use some creativity with your heads up strat. Heads up with low-moderate blinds can be a great way to steal a 1st against a bigger stack with solid play. Yes, with big blinds push/fold is the way to go, but with smaller blinds you have to fight a much more tactical battle. Some players get very aggressive heads up, and some start folding to everything. Getting a good feel for how your opponent plays heads up can turn a lot of 2nds into 1st's.