That's fine, mgm, but that isn't how it's working right now. All of the players who play the most in the formation used the most may be getting credit for starts, but aside from that, the percentage is much lower than 60% for everyone else. It's more like 30%.
Using tubby7242 from above again as an example. He has 6 OL credited with starting every game. It basically comes down to his SO OL Hopkins and his FR OL Starks. Now if you want to assume that one of those two is playing the majority of the snaps in the formation that he uses most often every single game that's fine, that would explain why one of them is getting a start. The other has gotten a start every single game and has never reached 60% PT in any game this season.
I use two offensive formations and I have the same starting RB in both formations. He starts every game. Now 3 times this season, out of 15 games, my backup RB has been on the field over 30% of the plays (31%, 31%, and 43%) all three games he was credited with a start. He would not have qualified for a start using either of the criteria you have listed.