How did the big spenders in free agency perform in the 2015 season?

"Free Agent Spending"= Total Contract Value/ Total Years
"Win Differential"= 2015 Wins-2014 Wins

Were teams who focused on re-signing players, rather than signing new players, more successful?

Sources:
SB Nation (http://www.sbnation.com/nfl/2015/3/10/8150357/nfl-free-agent-signings-tracker-2015-rumors)
www.Spotrac.com