Just for laughs, and because I have some time on my hands at work today, I went through the playoff brackets from last season in football and boys and girls basketball. Here's what I found:
Football:
6A - 2 of final 16 teams were non boundary, 1 of the final 4
5A - 1/16 and 1/4
4A - 7/16 and 4/4
3A - 3/16 and 1/4
2A - 3/16 and 0/4
1A - 2/16 and 0/4
Appreciate the analysis. One thing this doesn't cover is the number of non-boundary schools in each classification and how bracket mechanics dictate where they fall in the state tournament. For instance, in 6A the ONLY non-boundary schools are the four PCL schools and Pittsburgh Central Catholic. The PCL will always have one of the final 16 teams because that is where their champion advances. If PCC makes the WPIAL final, they are also in the final 16. It is the max that 2 of the 16 teams in 6A can be non-boundary.
In 5A, the ONLY non-boundary schools are the PCL schools. So, while the numbers look like "only" 1 out of 16 and 1 out of 4 teams are non-boundary, that is the maximum that can happen in the classification. And that team has won every playoff game it's played in both years of the 5A classification by lopsided margins.
4A is where there are the most non-boundary schools. By my count there are 10, coming from D3, D11, D10, and D12. By bracketing, it is possible to have 8 of the 16 teams be non-boundary in that round. It wasn't this year because Allentown Central Catholic and Bethlehem Catholic played in the round of 32 rather than the round of 16 based on bracketing. In this classification, the non-boundary schools were ONLY knocked out by each other, there was not a playoff win by a boundary school over a non-boundary in the 4A playoff statewide.
3A it is possible to have 5 of the 16 first round spots occupied by non-boundary schools. The two that did not make it were Mercyhurst Prep in D10 and Notre Dame in D11. They are each the only nonboundary schools in their district. Middletown was the nonboundary killer here, knocking out Conwell-Egan and Scranton Prep on their way to the state final.
2A can have up to 6 teams in the round of 16, but that would require all 3 WPIAL non-boundary schools to not hit before the WPIAL semifinals. In this classification, only Neumann-Gorretti won for the non-boundary schools against a boundary school in the state tournament.
1A it looks like there are possibly 7 non-boundary schools that can be represented in the round of 16, assuming all four of the WPIAL non-boundaries do not hit in earlier rounds of the playoffs and the two D6 non-boundaries don't either.
By that math, here is the breakdown of boundary schools in the round of 16 and the final 4 given the possible slots due to league and bracketing.
6A: 2/2, 1/2
5A: 1/1, 1/1
4A: 7/8, 4/4
3A: 3/5, 1/3
2A: 3/6, 0/3
1A - 2/7, 0/3