It was not too long ago, say 2011, that Branislav Ivanovic was the clear weakest (attacking) link in the Chelsea squad. Sir Alex Ferguson, in our Champions League meetings for example, used to specifically set up his Manchester United side to simply ignore Ivanovic. This allowed them to easily overload the middle without any real detriment thanks to the lack of tangible threat posed by the converted center back. Ivanovic may have been named to the Premier League's team of the year in 2009-10 as a right back, but he was still primarily seen as a center back who could be used as a mostly defensive option on the right -- and he remained in that role until Jose Mourinho came back.
The improvement in Ivanovic's overall game of course didn't happen overnight, though it was Jose who has given him license to roam forward pretty much at will, while surprisingly moving Cesar Azpilicueta to the left and keeping him as the more defensive of the two full-backs. Ivanovic has become one of our main avenues of attack, patrolling the right flank, providing width, crosses, and cutbacks. He's also one of the main outlets for Courtois' goal kicks.
What seemed like a straight swap [Ramires for Matic] actually led to the reorganization of Chelsea's whole formation. Willian went from freely buzzing all over the field to actually sticking to his nominal role on the right. And Ivanovic turned into a central midfielder.
A central midfielder? My word.
If that's not enough of a tease for you to click over and read the rest of MLG's piece, maybe this will.
In effect, Ivanovic's defensive versatility allowed Chelsea to change their approach and dominate the game. He has earned lots of attention for his attacking prowess, and deservedly so, but it's really his malleability that makes him a perfect fit for Mourinho.
For a team that wants to maintain that fungibility but generally not change its personnel, Ivanovic is so valuable. There's not another player in the league who can run a whole wing by himself, act like an extra center back on set pieces, and, in a pinch, become a better defensive midfielder than the guy who was starting. Oh, and if you need an emergency center forward, he can do that, too.
Branislav, a reaction?