Sterling leaving Man City for Chelsea is most intriguing transfer this summer

Of all the sub-plots underpinning this summer's transfer whirlwind, the one involving Raheem Sterling is the most intriguing.

The England winger, finally confirmed as a Chelsea player, is still only 27. He is still in his prime. He still has the guile and goals to provide the consistency his new team is crying out for.

Could Pep Guardiola, who has allowed the likes of Sergio Aguero, David Silva, Vinny Kompany, Yaya Toure, Joe Hart, Leroy Sane and Fernandinho to leave Manchester City without regret, finally have slipped up?

Could Sterling, the 2019 Footballer of the Year, a man with an outstanding fitness record and arguably the Player of the Tournament at last year's Euros, come back to haunt his former boss?

"I arrived in Manchester as a 20-year-old," he wrote in his open letter to City fans on Wednesday. "I leave as a man."

That will be music to the ears of Chelsea fans searching for heroes with Antonio Rudiger now at Real Madrid and skipper Cesar Azpilicueta finally set for his move to Barcelona.

Sterling arrives as a leader. A four-time title winner. Of all the non-strikers in the Premier League, only Frank Lampard, Steven Gerrard, Mo Salah and Sadio Mane have scored more than his 109 goals. Last year, despite just 23 Premier League starts, his 13 goals were still more than anyone in a Chelsea shirt.

Thomas Tuchel's Blues team are in a state of flux right now with the likes of Hakim Ziyech, Christian Pulisic and Callum Hudson-Odoi all set to be loaned out or sold after flattering to deceive. Sterling arrives with solutions on that left side of the Chelsea attack. Gareth Southgate swears by him for England, regardless of what might be going on at the Etihad.

Jack Grealish has some big shoes and even bigger numbers to fill in Sterling's absence next season. Phil Foden, of course, can play on that left side too and Guardiola will counter, justifiably, that his job is to build a City team for the future.

But there remains a sizeable body of opinion that Chelsea have landed a transfer window bargain. A wideman hungry to prove a point and capable of proving the difference.

New Blues owner Todd Boelhy cannot believe his luck. The American billionaire is delighted to have made such an early statement of intent as he bids to make good onto his promise to keep Chelsea competitive. As for Sterling, he has now joined Daniel Sturridge and Nicolas Anelka to have pulled on the shirt of Liverpool, City and Chelsea in the Premier League.

"I am thankful for the ups and downs," he added in his open letter. "As it's the downs that have, at times, tested my strength and resolve and enabled me to stand here in front of you as the best possible version of myself."

Chelsea fans will take that version.

Sterling has landed here in California on the first leg of the club's pre-season tour. He won't play in Saturday's first game against Club America in Las Vegas. But he'll be keen to hit the ground running so that when the season starts he can continue to show that best version of himself.

City fans will watch with interest.