Chelsea have plenty of areas to improve upon this summer as Frank Lampard prepares his team to challenge for the Premier League next season.

Fixing the defence has to be towards the top of the to-do list, with the Blues conceding a total of 54 goals this season; that is the same amount as Brighton – who finished 15th – and it’s 21 more than first-placed Liverpool.

When such a weakness is apparent, the usual solution at the top of the English game is to throw money at the problem by investing in new defensive players, and that is why many are confused by the club’s lack of interest in Nathan Ake.

The Dutch centre-back used to be contracted to Chelsea before moving to Bournemouth. He’s since seemed a capable talent at the top level but the Cherries recently suffered relegation, which has allowed Manchester City to poach him for a fee in the region of £41m.

The Blues have the option to match City’s bid due to a clause in the contract that took him from Stamford Bridge to the Vitality Stadium, but Lampard supposedly has no desire to sign him.

Considering Chelsea’s defensive record this season, some supporters are surprised but once analysing how they concede goals and how Ake performs, it becomes clear why Lampard is avoiding his signature.

Although 54 goals have been shipped, their defence, on the whole, has actually not been as bad as that number may suggest. Expected Goals – which can offer an insight into whether a team deserved to concede fewer or more goals based on the locations of their shots faced – captures the Blues in a positive light.

They had been expected to concede just 38.2 times which is the fourth-best in the division, but they have actually shipped around 16 more.

That underperformance was mostly because of two things. Firstly, Kepa Arrizabalaga saved shots at a worse rate than any other goalkeeper in England’s top-flight by some distance, and secondly, set-pieces.

Shots that derive from corners are typically valued as low-quality efforts by xG, as they aren’t scored very often and they are usually struck using the head of a player rather than his foot.

However, although they are perceived as low-quality opportunities according to xG, Chelsea conceded from many dead-ball situations. Of the 54 goals that were shipped, 15 were from set-pieces.

So where does Ake come in? Well – amongst his strengths – the 25-year-old has a very obvious weakness, with that being that he’s not very good in the air.

Standing 5-foot-11, Ake isn’t the dominant aerial presence that Lampard’s outfit would benefit from, with the Blues boss stating recently that a potential solution to his team’s set-piece woes is signing taller players.

Some 50 central defenders amassed over 1,500 minutes in the Premier League this season, with Ake placing 49th for aerial duel success (%).

If the sample was to include Europe’s top five leagues – with a total of 234 centre-backs – Ake places 221st, with Kurt Zouma impressively ranking third overall.

Money can fix certain squad issues but simply buying another defender wouldn’t have resolved Chelsea’s problems very effectively. He’s a good player but Lampard is right, he’s not what the Blues need right now.