While I agree with most of this, allow me to make three points.
1. Durability is important. Although Drew has a good career OPS, if he averages only 64 total RBIs a year, he is underperforming. A 800 run team should expect to get at least 100 RBI out of a $14 million middle of the order hitter. Of course, aside from only one season in his 11 year career, Drew hasn't reached that threshold.
2. The 5-year $70 million commitment essentially locks the team out of considering a replacement if Drew is marginally underperforming. So the team needs to live with mediocrity if he doesn't produce.
3. I know I'm in the minority here, but I believe his defense is overrated. Does he have the tools? Yes. But, like all things Drew, the best shows up only sporadically.
So, while I don't believe Drew is among the Sox top five problems this year, his contract limits the Sox options as he continues to underperform.