I think people's assumptions were that they left too much cushion under the CBT. The problem is that the online tools that calculate the Sox' CBT aren't great at the moment. We now they are under, but can only guess at how far due to bonuses and other issues.
They can't go over this year, but I think people wanted them to get as close to the CBT as possible. Maybe some wanted them to spend like the Mets and Padres, but those are untrustworthy posters.