Originally Posted by goober
I know people who were bumped with very matches. A former team mate went 3-3 and was bumped to 4.5. His losses were 1-6, 2-6, 3-6, 4-6, 4-6, 1,6. Unfortunately one of his wins was a lopsided win against a ringer who threw the match against him. Completely unfair that he was bumped. He basically quit USTA after that.
Another guy was bumped to 4.5T after winning a a 4.0 tourney playing only 3 matches.
It all depends on your current rating when the sequence of matches starts, and then the rating of who you play and the scores. Depending on those factors, it could take just a few matches, or take many matches for someone to get bumped up or down.
You didn't say if the 3-3 teammate had that record at 4.0 or if he was playing up at 4.5. Losing against strong opponents can still improve your rating. And that lopsided win can skew things, particularly if the opponent is or ends up being benchmark.
The 4.5T could have been very close to the threshold to be bumped, and then just 3 matches with good results against strong opponents can easily push him over the threshold.