That’s not possible. 6.5-0.5 is not all wins. All wins does not mean undefeated; it means nothing but wins. And even with an all-wins rating, you can’t top 400 points over the highest rating ever faced. (And with the regular rating formula, you would need (many) hundreds of wins against 1400’s to get anywhere near 2200).
How many years ago? If it was since December 8, 1991, it should be part of MSA.
If it was before 2000-2001 (I’m not sure exactly when the new provisional formula took effect), then it seems even more implausible, because back then we averaged the result of W+400, L-400 over the players first 20 or 25 games. (It changed from 20 to 25 at some point, in the mid 80’s as I recall.)
Looking at the MSA detail (which goes back to late 1991), it appears that the most games anyone won before their first loss was 35 (the first loss in the 3rd round of an event in 2008) and the most games anyone lost before their first win was 130 (finally winning a game in the 2nd round of an event in July of 2018).
The peak post-event rating I see for someone with all wins is 2700, which has occurred for 3 different players in the regular rating system, for one player in online quick events and 2 players in online blitz events. I checked the code, the special formula caps a rating for a player with all wins at 2700 not 2800 as I posted upthread.
I haven’t found the player Rob was citing, but 6.5-0.5 could include a half-point bye or other non-played result, which would be ignored. I did find one TX player with a 6.5 score and all wins plus a half point bye, but his post-event rating was only 1160.