McClellin was a former college defensive end that converted to linebacker over his time in Chicago. He served under three different head coaches and defensive coordinators, and played three different positions as he failed to develop in the NFL.
Bill Belichick and the Patriots hope that some consistency can help McClellin back on track and revive his career.
Per ESPN's Adam Caplan, the contract details are pretty reasonable.
New #Patriots LB Shea McClellin signed a 3-year, $12m deal with $3.5m gtd, source said.— Adam Caplan (@caplannfl) March 19, 2016
While hopefully Dont'a Hightower and Jamie Collins sign long term extensions, McClellin can serve as insurance in the case of their departure. McClellin will slot behind Hightower and Collins, and ahead of Jonathan Freeny, with regards to contract values. While McClellin isn't of the same caliber as Hightower or Collins, he is better than Freeny and can step into that 3rd linebacker role and function on special teams.
The average of $4 million per year tag places him around the 50th highest paid player at the position, which is essentially a low-level veteran contract for a player expected to serve on defense.
$3.5 million guaranteed is actually pretty low for a player with a $4 million per season value, which means that McClellin will have one season to prove that he deserves to be on the Patriots, or the team will move on without much long term repercussion.
McClellin will add valuable depth on defense and special teams, is an improvement over Freeny, and provides insurance for Hightower and Collins. Hard to ask for a better linebacker signing this offseason.