The Senators protected a (then) 23 year old Ceci, who was selected 15th overall in the 2012 draft ......... and left an aging (then) 32 year old Methot exposed.
I don't know how many times the "Methot could have return for a 2nd round pick" myth has been debunked, but it was explained that the Senators tried to get him back from the VGN, but they were asking too much, and yes it was more than a 2nd pick for the Senators.
BTW, I doubt anyone would call Methot the Senators "2nd best D man" ...... but you can if you want, to advance your narrative ......... but yes he worked well with Karlsson, and that was his value to the Sens, and that same "chemistry" has not materialized with anyone else yet.
Also, I'd like to point out that Methot has only played 16 games this season, and has yet to register a single point, despite averaging over 19 mins per game.