Last year I played only 4 matches at 3.5 on a new team and lost them all (2 matches I lost in 3rd set tiebreaks). I would chalk the losses up to poor partner selection by my captain, bad luck, and obviously not getting the job done. It was a tough season.
In doubles, I regularly play with 4.0 guys at my club and hold my own. I would rate myself as a high-level 3.5 at doubles. I am in pretty bad shape, so 3.5 singles is tough unless I am blasting a lot of winners (it happens, but not often enough).
USTA bumped me down to 3.0 this season because I went 0-4 last year. At first I was a little sore, then mostly just incredulous. I would play up, but there's only one 3.5 18+ team at my club, and they aren't accepting new players (they go to sectionals most years). So I am a 3.0C this season.
Undefeated so far, and I don't see myself losing a match. The guys I play against must think I am the biggest sandbagger ever. So basically, I am that guy.