you see the hump in those distribution stats. It's almost certain that you are playing way to tightly and you leave yourself shortstacked when you are on the bubble. The number of 4th place finishes is way way too high. It's simple math and probability that if you are have a shorter stack on average than your opponants when four handed that you will bubble more often in the long run. Get a bigger stack than average when four handed and you will bubble less often get into the money more often, which of course leads to more first place finishes.
Of course it's not as simple as what i've stated above. You have to work on leaks, the hardest part of working on leaks is identifying them. Trackers help with this, especially ones where you can break your game down and focus on specific areas.
If you look at a winning players distribution you will see a noticeable differance.
Read through this as it explains what i'm talking about.
Basically you will likely need to loosen up more when 5-6 handed, to build your stack for the bubble. Yes your taking more risks, and you WILL be busting out more often in 5-6 place, however the stack you get more than makes up for this, as you will be left in a much better position to kind of bully your opponants when on the bubble, which leads to even more chips, which sets you up for more wins.
hope this helps.