Lets put my gorilla math to work.
133 planes * 10 fh/day * 31 day/month = 41230 fh/month.

41230 /70 fh per-pilot = 589 pilots *2 (you need a co-pilot) = 1178 pilots.

So my guess is right now Mesa is either fully staffed for pilots or close to it. Mesa probably wants a few more than that to cover training, sick days, misc coverage, so 1250 would be the ideal number of pilots...I think.

Am I close?