I'm glad you said you forgot that he was 19 when he made his debut all the way back in 99/2000, because I've pretty much stricken that from the record when judging his int'l career so far. Its just useless in basing how valuable he is today, and how valuable he will be in the future.
If we look at his test career since the Aus in India tour in 2004/05 until now (once again as you've noted, a stop-start career at that) it is this:
Code:
Mat Runs HS BatAv 100 50 W BB BowlAv 5w Ct St
unfiltered 9 398 91 26.53 0 3 0 - - 0 12 0
filtered 5 257 91 32.12 0 3 - - - - 11 0
Not outstanding, but far from poor. I thought he threw his opportunity away in Ahmedabad against Sri Lanka where he was preferred over Ganguly. Once he failed in both innings there, I thought he would be out of the picture for a while, particularly with Yuvraj's success in both forms and Kaif's ODI form against Pakistan being poor as well. However he got an opportunity against England, made the best of it and scored a good 91 in a pressure situation. I actually have no problem with him being dropped for the 2nd test, and never criticised India for doing so (this despite me being probably his biggest supporter on this board) because I do think Laxman is clearly the superior player and should have been preferred. When both were left out, well that baffled me. Particularly since Chawla didn't do very much in the test.
However furthermore, that 64 of his against Australia in Chennai was a wonderful knock. His 102 run partnership with Patel was vital in putting India into a commanding position in that game, and had it not been for the rain maybe it would have been a match-winning one.
None the less I think this discussions is just a difference of opinion which can't really be proven by stats or debate over his career so far. Only Kaif will really prove one of us right or one of us wrong. One thing is for sure, it will be intriguing to see how his test career goes in the future.