This is a cap move for the Blues. We needed the extra million+ Sanford makes elsewhere. This way we do not need to trade Tarasenko if we cannot find the right deal. The Blues were plenty deep already, so Sanford might have naturally been a 4th liner depending on how camp shakes out. Brown can compete for a 4th line/press box slot. If he plays well enough to earn it, great. If not, we got the cap space we needed.
I do wish we could have gotten a better player or higher pick coming back for Sanford though. $2M is not overpaid for what Sanford brings, so he is not a cap dump. He should have some value. He is frustratingly inconsistent and bone-headed at times, but he also puts up points overall. I am not a Sanford fan at all, but the Blues might end up missing him if they do end up trading Tarasenk for a LD (like they should). 2 top 9 forwards traded would hurt our forward depth a bit.