Mats Hummels Transfer Link Leaves Question Mark for Gary Cahill at Chelsea

Is Gary Cahill set to be the next casualty in Jose Mourinho’s mission to establish Chelsea as a European force?

If Mourinho makes good on the rumours in The Telegraph and elsewhere that he will join the chase for Mats Hummels this summer, it will surely spell the end for Cahill at Stamford Bridge.

John Terry’s recent contract extension has given Mourinho the stability he needs to continue his transformation of this Chelsea side ahead of the 2015/16 campaign.

Knowing he will have his captain around for at least one more season allows the Chelsea boss to focus his attentions on other areas of the squad he feels are weak—namely in midfield, where reduced numbers have limited his options at times.

Retaining Terry’s services also gives Mourinho another 12 months' grace to identify and secure the defender's replacement; the likes of Kurt Zouma will have another year’s experience to prepare for the first team proper.

With the emerging talent Chelsea have in defence, it’s not those young players’ futures that are at risk. If Mourinho’s looking for another established name, it’s Cahill who will pay the ultimate price.

Hummels wouldn’t be moving to west London to warm the bench. Mourinho wouldn’t be signing him to do that, either. Like Cahill, the German has achieved enough in his career to not only command a starting place wherever he travels but demand one.

He’s an established star, and players of Hummels’ ilk aren’t purchased with squad depth in mind.

With Terry very much No. 1 at Stamford Bridge, where would that leave Cahill?

Michael Regan/Getty Images

The centre-back has already had to fend off a challenge from Zouma this season, but it’s clear Mourinho’s plans are more long-term with the Frenchman. Whereas Zouma was a ruse to remind Cahill of his own mortality—which worked—it’ll be an altogether scenario with Hummels.

Mourinho rightly opted for Cahill over David Luiz when it came to that particular battle, although a loss of form before and during Christmas was a warning the manager couldn’t ignore.

He drafted in Zouma to show Cahill his place is at risk when standards drop, and it got the desired result: He rediscovered the type of form that has made him a well-respected figure on the Stamford Bridge terraces.

Is Mourinho doubting that Cahill can no longer produce in the same way he has, though?

It’s one thing to use an eager youngster like Zouma to entice more from an experienced player, but quite another to sign a player of similar standing.

Richard Heathcote/Getty Images

Hummels would be arriving as Cahill’s replacement.

With a World Cup winners medal on his CV, some will point to Hummels as the superior defender, both in presence and talent.

The truth is, there’s little between him and Cahill. Indeed, they’re similar types, and Hummels would certainly complement Terry in that vital central-defensive pairing.

Hummels is good on the ball and reads the game well, and his more cultured attributes are akin to Cahill’s approach, a factor which has helped re-establish Chelsea’s solid foundation at the back.

Mourinho puts plenty of emphasis on that defensive strength, understanding the need for consistency from his players. That comes with familiarity, and it's rare that he rotates his central defenders. It happened rarely when Terry partnered Ricardo Carvalho, and it's been the case now with Cahill.

Mike Hewitt/Getty Images

There isn't room for three big characters. The balance for Mourinho is to have his first-choice partnership as strong as possible, with less established names capable of slotting in when required. It was the role of Robert Huth before; now it's Zouma's.

With Hummels on the scene, Cahill would be squeezed out of the picture.

Should the situation develop that far, it would be a shame. Cahill's been a fine servant since he joined Chelsea in January 2012. His story is one of the underdog, the unfancied player who arrived from nowhere to make a name for himself in west London.

Cahill has the talent and he has the character, too, as he explained to the Evening Standard only last month. "Having people doubt you is what gives you that fire in your belly. It’s got me to where I am today," he said, explaining how he has proved the doubters wrong over his career:

Mike Hewitt/Getty Images

"

When I was at Bolton, I went to England and people said, 'he can’t play for England'. I proved them wrong.

I came to Chelsea and people then said, 'this guy can’t play in the Champions League' and I proved that wrong.

There are challenges in front of you that you face all the time in football. You ride through and come out the other end.

I have proved it time and time again and I will prove it again. In my mind there is no issue.

"

Cahill will need all that resolve and more if Mourinho moves for defensive reinforcements this summer.

Garry Hayes is Bleacher Report's lead Chelsea correspondent. All quotes were obtained firsthand unless otherwise noted. Follow him on Twitter @garryhayes