Matt Walker joins the Tampa Bay Lightning

Defenseman Matt Walker, who played for the Chicago Blackhawks last season, is joining the Tampa Bay Lightning defensive corp. The deal is for four years and $6.8 million dollars in total.

Walker's 11 year career had him playing a smattering of games per season with the St. Louis Blues up until last season when he joined the Chicago Blackhawks. In 65 games with the playoff bound 'Hawks he had 14 points and was plus seven. That seems to be the big noteworthy thing about him - he is relatively stable in that area and not a sieve. He's a lower pair defenseman though.

How does this signing effect the Lightning depth chart on the blue line?  Who stays and who is AHL bound?