There were 88 contestants in PSL3 (less Mr. Sheep). 68 of them are in PSL4. That is a 77.3% re-participation rate. PSL1 had a re-participation rate of 78.9% (60/76) and PSL2 was 78.4%. All three are amazingly similar.
We have 6 newbies. Good luck to you new guys, but we don't start Freshmen at PSLU! Of course, I said the same thing immediately before PSL2 and the winner was a newbie as were 5 of the top 7 humans!! However, PSL3 was more as one would expect. Only one person in the top 37 (StyleCounciler #5) was a PSL newbie.
Naturally one would wonder if the re-participation rate for PSL4 was correlated to where they finished in PSL3. There is a small correlation, but not much of one. Shown below is the first group of 10 in the final PSL3 rankings and how many of them (10) are participating in PSL4, etc. Re-participation rate for PSL3 is based on how each group finished in PSL2 and the same thing for PSL2 based on how each group finished in PSL1.