Clearly, Berglund is worth a LOT less in trade if he's unsigned. He probably didn't cooperate with Army on The Blues' offer, so, Army wanting to use Bergland as one of the main "current roster" player assets in the trade for Spezza, had to give in and "overpay" Berglund a bit, to get him signed, and "tradable". As it turned out, The Blues were able to "agree"(at least get a pretty good idea they were going to end up with him) with Stastny during the 5 day window, and then with Ottawa holding out for an unreasonable price for Spezza (Schwartz included), The Blues gave up on Spezza, and ended up having to keep Berglund at a "higher than wanted" $3.7 million.
Given that The blues would have been worse of getting Spezza if they had to give up Schwartz, I can live with their keeping Berglund at his new salary. He's still a decent trade chip, if Army waits for an opportunity caused by another team's injury before this or next season's trade deadline. In the meantime, having a 3rd line of Berglund-Lehterä-Tarasenko or Berglund-Sobotka-Oshie won't be bad at all, considering what Stastny adds to the team, AND that with Morrow, Roy and Ott gone, The Blues are a team full of young players and players in their prime, other than only Jackman. I think I'd rather have that than adding a downward-headed, Spezza, with back problems, and a high salary for several years.