Paul Stastny helped Mueller put up 20 points in 15 games to close out the 2009-10 season, before the concussion issues began the following year. When the lock-out ended, he joined the Florida Panthers, but had to sign in Switzerland for 2013-14, where he posted 46 points (on 24 goals) in 49 games with the Klöten Flyers.
He signed a two-way deal with St. Louis, but if he does well in training camp, I think he'll have a legitimate shot at the first line, which would help keep the Blues' other - and current - lines more or less intact despite the arrival of impact franchise center Stastny. If he has to start the season in the AHL, I'm somewhat convinced he'll be back come playoff time as the Blues try to fend off other top-level teams such as the Los Angeles Kings, Chicago Blackhawks, Dallas Stars and Anaheim Ducks.
In the meantime, here's a card showing him wearing the Avs' burgundy (home) uniform (with a matching jersey swatch), but listing him with the Panthers, from Panini's 2012-13 Titanium set (card #GG-PM of the Game-Worn Gear sub-set):