I respectfully disagree with you here.
Let's look at his tests:
1. 3 Tests in Australia 2011-2012 -
No finger spinner does that well there. Barring Lyon of course (home). Even Murali wasn't at his best here. Add to the fact that whenever Ashwin came on to bowl, the score would be a good one with well set batsmen. In Sydney he didn't pick up any wickets but did okayish in Adelaide and Melbourne (I am NOT saying he did satisfactorily....no no....but it was surely not garbage in the context).
2. Joberg - Screwed up. Deserves blame. Known as a spinners graveyard. 10 years back Kumble and warne took a 3 wicket haul there. But he should have taken atleast 1-2 wickets. Got dropped JUST befor the Durban spin track.
3. 2 tests in England (bowled 2 innings) - 0/35 and 3/75 odd. Avg 35. Bowled much better. No scoreboard pressure, pacers were all over the place (4th and 5th test). I felt he bowled decently.
4. 2 tests now in Aus. You saw him.
Where did he overstay his welcome?
3 tests in Aus and Joberg was his mistake.
In England, a lot of posters said he looked more threatening than Jaddu. With many lefties in England side, I always felt Ashwin would do something.