I was surprised when I saw this.  I hope he is doing more in practice than he has been doing in games.  I see him as being a little too slow.  Just doesn't seem to have the foot speed to keep up with the game at his position.
Like others have said, as the 14th or 15th guy on the roster, I will trust that the decision makers see some remaining unfulfilled ceiling and they want to give him another season.  I am surprised, I am not seeing it, but so be it.
Walsh has a Jan 10 guarantee deadline for the second half his salary this season and the team still has an option for next (about $2.4M).  This may not bode well for Walsh.