The best barometer of how much better Youkilis is now might be found in his failure and success with two strikes. When Youkilis was a rookie, he hit .181 with two strikes. In 2005, he batted .264 with two strikes; 2006, .246.
Youkilis, in 2007, is ranks fifth in the majors with a .327 batting average with two strikes. That means he's improved more than 140 points in that situation over the last three years. Not bad.
Olney compares Youk to Boggs, which is an interesting comparison. It's a good read.