David Luiz is now officially a Chelsea player, signing a five-and-a-half year deal (according to SB Nation community blog We Ain't Got No History). Completing a deal that was on again, off again two times today, the 23-year-old Brazilian defender moves for a minimum €25 million, with midfielder Nemanja Matic also said to be moving to Benfica at year's end as a makeweight.
While the Fernando Torres acquisition will rightfully garner the greater headlines, Luiz's signing may be a bigger immediate need. Even when healthy, Chelsea's defending has proven more questionable than in previous seasons. At the top of an increasingly competitive Premier League, that slip would be enough to see them fall behind Manchester United. That their midfield also went through a disastrous spell in the season's first half meant Chelsea went crashing to the edge of the league's Champions League spots.
Increased health has seen the midfield problem solved, and with the acquisition of Luiz, some of the issues the club faces at the back will be augmented. Depth in central defense has been a problem since before Alex's knee injury. In addition, the defense has looks slow and unathletic, at seems appearing to unduly rely on Branislav Ivanovic. Luiz's acquisition may not do anything to decrease that dependence, but at least it allow sAncelotti to use Ivanovic on the right, spelling the increasingly fragile and decreasingly effective (defensively) José Bosingwa.
The biggest question is how Luiz may fit in on the right of John Terry, with both Luiz and the Chelsea captain accustomed to playing on the left of a central pairing. That, however, could prove to me a minor concern, with a talent like Luiz likely to overcome a potentially minor positional adjustment.