I didn't notice that Bouma ever stopped giving shots even after the Letts punch. You are right, Letts threw a punch, but, I didn't see Bouma stop giving the shots. I did notice Calla make an effort to get a one/one battle going with Bouma so that Bouma would be paying attention to him, not Bowman - considering Bowman and Calla were on the ice at the sametime - and often, at least in Vancouver, Bouma was out with the Bowman/Calla line.
Either way, Calla did try, and so did Letts - not sure either were ultimately that effective. I question that Letts actually made anyone on the Vancouver side actually change their game. After all, Kane threw the knee out on Spurgeon, which was answered by Letts knee on Kane later in the game...and then the next game, Kane wasn't too intimidated by Letts or any retaliation from the Chiefs, as he gave Tokarski a stick to the neck.
However, I'm not saying Letts or Donny aren't justified 20 year olds in this league. And, I'm certainly not saying the tough guy doesn't have a place on the team. I'm just saying other guys may have had just as much of a positive effect as Letts/Donny...such as Calla. Just wanted to throw his name out there was all.