Yeah, his best season was 2008-09. He had more of everything in 2008-09 because he stepped up when Manu missed half the season.
Lately, Parker hasn't been as quick on defense but I've chalked that up to his calf strain. Who knows what else has going on with him after 65 games? He started off the season in the top 20 in steals, but as the season has worn on, he has leveled-out a bit. His last 4 games he's averaging 2.0 SPG, though.
It's interesting that you posted this after he shot fairly well from the perimeter against the Kings (5-7 and 2-2 from the arc). I think it has been Parker's best year in his over-all play and feel for the game. It is also one of his best 3-point shooting years. He's worked on it and as a career .315 shooter from the arc, he's shooting .380 this year. He really only has had one decent 3-point shooting year since Pop trimmed his wings on shooting them. That was in their last championship run of 2006-07 (.395 with only 15 makes).
He is a very accomplished passer, now, out of screen/rolls. He's looking to assist on a more regular basis. In fact, I wish he would look to pass more often. As we know by now, the Spurs are undefeated (29-0) when TP has 7 or more assists. In their 11 losses, he's averaging 3.5 APG. In their wins, he's averaging 7.2.
He has better options for scoring than he has had the past several years. Tony did a poor job of seeing and finding open men vs. the Kings. But over all, I think this is TP's best year. When he plays poorly, he impacts the success of the Spurs much more than if Tim or Manu have a bad game. The stats bear that out.