Chelsea‘s exile from the transfer market is finally over.

Today the Court of Arbitration for Sport halved the Premier League club’s two-window registration ban and, given they didn’t sign players in the summer, the Blues are free to enter the January window.

The first position that will need improving is left-back – as discussed in more detail here. But, according to The Athletic, Chelsea are also interested in strengthening their options in attack.

A well-rounded alternative to Tammy Abraham is wanted. As is another winger, especially given Pedro and Willian are out of contract next summer. Supposedly top of the Blues’ wishlist is Crystal Palace winger Wilfried Zaha.

The Ivory Coast international has wanted out of Selhurst Park for some time. So much so, he handed in a transfer request at the end of the summer window amid interest from Arsenal.

Wilfried Zaha, Crystal Palace

Palace demanded a fee of around £80million for the 27-year-old and that, rather unsurprisingly, put off the Gunners. And so Zaha stayed with the Eagles against his will.

Perhaps as a consequence, the winger wasn’t at his devastating best in the early weeks of the campaign. He didn’t claim an assist until late September and only got on the scoresheet for the first time on November 23.

But he followed up his goal against Liverpool with a strike against Burnley and was also lively as Crystal Palace defeated Bournemouth despite having ten men for over 70 minutes.

That is all well and good. But given Chelsea would have to pay £80million – a fee that would make Zaha the joint tenth-most expensive player of all time – is the Palace winger doing enough on a consistent basis? And would he be an upgrade on what the Blues already possess?

If we compared the former Manchester United winger’s output and expected output this season compared to last, it’s clear there has been a drop off in his effectiveness.

Wilfried Zaha comparison

There are caveats to the numbers in the above graphic, though. In the opening months of last season, Zaha was often used through the middle by Roy Hodgson. And he responded with three goals in his first four matches.

This term that hasn’t been the case. Zaha has almost exclusively been used out wide and, as the heatmap on the right shows, he has split his time between the left and right flank.

This lack of consistency will have impacted Zaha’s output, something which shouldn’t be forgotten when looking into the pure numbers.

There is little point in comparing the Palace talisman to Chelsea’s current wide options either. The Eagles are a defensively-minded side, one that is set up to be difficult to beat first and foremost. Frank Lampard’s Blues, meanwhile, are built to attack.

It will not come as a surprise that Willian and Christian Pulisic have a better goals per 90 record than Zaha. Nor that Callum Hudson-Odoi creates far more goals on a per-90 basis.

The one area where the Ivorian does best the Blues trio is dribbles per 90, but that is because he is often charged with bringing Palace up the pitch to alleviate pressure.

So perhaps the best way to evaluate Zaha is to look at his underlying numbers. Last season he struck ten Premier League goals, all from open play. It was his best return in the top flight.

Yet his open-play expected goals total stood at just 5.74 and his post-shot expected goals, which takes into account not only where a shot is taken from but where it was placed on target, was 4.63.

This suggests Zaha’s goalscoring form from 2018/19 was unsustainable. He wasn’t getting high-quality chances, nor was he adding value to the attempts he did have through finishing skill.

He has reverted to the mean this season. Zaha’s has two goals, again both in open play, from an open-play expected goals total of 2.05 and a post-shot expected goals figure of 1.82.

Once again the counter-argument is Palace are not prolific chance creators. And it’s a fair point. However, Southampton or Watford have hardly set the Premier League alight this season yet Nathan Redmond (2.17) and Gerard Deulofeu (2.15) can better Zaha’s open-play expected goals.

There is little doubt that the 27-year-old is a vastly talented footballer. His skill and trickery on the ball can delight fans. But that isn’t enough for Chelsea, especially if they have to pay £80million.

Lampard’s side need a consistent end product in the final third and that is not something Zaha can ensure. He would be an expensive gamble, one the Blues do not need to take.