The ones that got away: Would Mourinho exiles really improve Chelsea?

Mata has generally been used by Louis van Gaal on the right this season, where he has made a good impact for Manchester United. Three goals and three assists in eight Premier League games is a return that beats any of Mourinho's squad. Pedro, who occupies that berth for Blues, has managed nothing to trouble the scoresheet since a brilliant opening showing in which he notched one goal and one assist against West Brom.

However, the reasons why Mourinho offloaded Mata remain: his unremarkable pace (a good deal slower than Pedro) and reluctance to track back (which has resulted in goals conceded by United). Chelsea have more of a need in the heart of midfield, but the one occasion on which Mata was tried there this campaign resulted in probably his worst performance of the season, away to PSV Eindhoven.

Verdict: Unlikely to improve Mourinho's Chelsea as either a classic right winger, or a central attacking midfielder. Might give something extra in the more withdrawn Cesc Fabregas-role, but would he be content playing there?

At joint third in the scoring table, and with four more than Diego Costa's lone effort, Lukaku looks like the ideal solution to Chelsea's Premier League goal drought. The Belgian seems to have come of age this season at Goodison Park, and some have pointed wryly in his direction in response to Costa's off-the-boil run.

But again, the issues that led to his departure from Chelsea remain: it seems implausible that Mourinho would consider picking a player who contributes so little defensively to the side, and Costa's team effort would surely keep him in the driving seat for selection. That would mean Lukaku relegated to second choice, a place he has made it clear he simply doesn't see himself occupying.

It is notable also that Lukaku's goals tend to come in clusters against teams on an off-day. Beggars can't be choosers, and Chelsea would take them anywhere, but it has to be wondered if he would be quite so prolific against sides playing on the counter, as they often do against Chelsea.

Verdict: Without substantially changing his game, unlikely to add more goals to this Chelsea team than he might cost through his low work-rate.

Once or twice, those watching Gary Cahill and John Terry this season might have considered that the pair of them have caught something from David Luiz. The lapses in concentration - momentarily disastrous brain freezes that cost goals – have been a hallmark of pretty much all of Chelsea's centre-halves this season.

But both of them, and Kurt Zouma too, look an improvement on the World Cup worst we saw of Luiz for Brazil.

Verdict: It doesn't bear thinking how many goals Chelsea might have shipped this season with Luiz in that back four.

At first considered the ideal Mourinho man, but then suddenly fell out of favour before last Christmas – and wanted out. The Chelsea boss saw it as a straight battle between Schurrle and Willian, picking the Brazilian for his superior team effort.

Many complained at the time that Willian was less adept at taking goalscoring chances than the man Chelsea lost to Wolfsburg, but the last few games should have changed that opinion.

Verdict: Willian won the battle a year ago, and he still wins it now.

Chelsea's full-backs have been one of their key problems this term, with the man at right-back, Branislav Ivanovic, roundly considered the weakest of weak links in the team. Logic says he should be dropped, and Cesar Azpilicueta moved over, but Mourinho insists new left back Baba Rahman is not ready for Premier League action.

Bertrand showed, in Southampton's recent 1-3 win at Stamford Bridge, that he is more than ready for that.

Verdict: Would walk into this Chelsea side tomorrow, and improve it too. Chelsea miss their Champions League winner - but would he get a game once Rahman is acclimatised?