One or two good seasons with a lot of crap in between.
Okay, this is patently false seeing as though he's been IPL MVP twice, but let's explore it anyway.
2008: 15 matches, 472 runs @ 47.2 (S/R 151.76). 17 wickets @ 22.52 (Econ 7.07) IPL MVP.
Best player in the tournament, opened the bowling and batted top 3 the whole series. Dominant.
2010: 6 matches, 185 runs @ 37 (S/R 162.28). 6 wickets @ 30.66 (Econ 8.36)
Didn't play many games (can't remember if injury or other commitments), still pretty good especially with the bat.
2011: 11 matches, 330 runs @ 33 (S/R 130.43). 6 wickets @ 40.16 (Econ 6.69)
Poor series by his standards. Batting still very good but S/R is down. Wicket-taking ability is down with the ball but the Econ is very good.
2012: 7 matches, 255 runs @ 42.5 (S/R 151.78). 6 wickets @ 26.83 (Econ 7.00)
Again don't remember why he missed matches, but both the batting and bowling are fantastic. Especially his S/R and Econ rate. Would say this is a very good season but for the missed matches.
2013: 16 matches, 543 runs @ 38.78 (S/R 142.89). 13 wickets @ 22.92 (Econ 7.15) IPL MVP
Absolutely dominant again, especially his bowling.
2014: 13 matches, 240 runs @ 20.00 (S/R 122.44). 7 wickets @ 23.57 (Econ 7.85)
Worst season to date with the bat, nothing redeeming about it. Bowling again very good but a little expensive. Poor season with the bat means even though he bowled well, it was in short spurts and didn't contribute much.
2015: 10 matches, 347 runs @ 43.37 (S/R 135.01). 6 wickets @ 44.83 (Econ 9.27)
The batting is back in a big way but the bowling is equally gone in a big way. Poor season, but still contributes strongly as a batsman.
2016: 16 matches, 179 runs @ 13.76 (S/R 133.36). 20 wickets @ 24.25 (Econ 8.58)
Batting gone again, but probably his best season with the ball despite being a little expensive.
Won't bother with 2017 as he's only played a few matches.
Overall, his stats are as follows:
98 matches, 2611 runs @ 31.84 (S/R 139.32). 83 wickets @ 27.95 (Econ 7.82).
He's 15th on the list for total runs (and other than Chris Gayle is the only person in the top 15 with less than 100 matches).
He's 17th on the list for total wickets.
His age has robbed him of his ability to consistently perform in both disciplines in recent seasons, but to have a top 10 IPL players list without him is absurd IMO. Saying he only had 1 or 2 good seasons is also just straight up false, he hasn't even had a season where he didn't contribute positively in at least one discipline.