I don’t doubt he’s a good bowler. I think that he would be more effective in a better team and used in a better way. Because the Heat have quite a weak bowling line-up the opposition know they can just hit him for a run a ball and then attack the others. Also the Heat often bowl him in the powerplay so he has to be defensive with his line and length. If they gave him more opportunity in the middle overs when he could have defensive fields then he could attack more.
Sure you’d expect subcontinent spinners to do better at home but actually the pitches they use in Australia at the moment tend to be quite slow and low so those bowlers should and are doing well