It looks like he's on the right track, as the changeup has climbed to just under 40% - not quite his peak, but that kind of rate is still more than 20% better than league average. As it was earlier in the season, his fastball is looking great.
A Baseball Weblog
Thursday, August 25, 2011
In July, before Rich Harden's last start against the Yankees, I briefly examined his 2011 whiff rates compared to his previous seasons. After a terrible 2010, his fastball was back to its normal excellence, but his changeup remained at/slightly under the league average after being one of the best bat-missers in the league in 2008 and 2009. The same chart is shown below, updated: