When Everton shelled out £25million on Yannick Bolasie during the summer transfer window, plenty of eyebrows were raised.No doubt, the Congo international improved his game at an incredible rate during his time at Crystal Palace, establishing himself as one of the most feared wingers in the Premier League's bottom half, with that unpredictable, unconventional dribbling style making him a real nightmare for defenders.But £25million seemed incredibly steep for a 27-year-old already at his footballing peak, who had managed just nine goals (three of which came in a single game) during three top flight campaigns at Selhurst Park.Now ten games into his Toffees career, however, and few Everton fans are still questioning the fee Ronald Koeman paid - which is actually the second-biggest throughout the Goodison outfit's history.Indeed, Bolasie's undoubtedly added a new dynamic to Everton's attack and we've got the stats to prove he's arguably the Premier League's signing of the summer...

Everton's spending-to-points surplus

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A curious piece of analysis courtesy of Transfermarkt, comparing net spend during the summer transfer window with current positions in the Premier League.

As you can see, Everton were one of the few clubs to have a positive net spend during the summer, therefore ranking 18th throughout the division, and now find themselves in sixth place - giving them a difference of twelve.

Only Liverpool have fared better in this regard and although that can't entirely be put down to Bolasie, he has played a major role as Everton's biggest outlay. If the Congo man wasn't in such fine form, Everton would likely be much further down this unique table.

Premier League's third-best dribbler

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We've already touched upon the Congo winger's dribbling ability but here's statistical proof of how effective and consistent a ball carrier he actually is.

Indeed, he ranks joint-third throughout the Premier League for successful take-ons so far this season, level with Manchester City's Raheem Sterling and just two places behind Chelsea's Eden Hazard.

Considering how much their respective employers would demand for Sterling, Hazard and fifth-place Alexis Sanchez, £25million seems like an absolute steal. Courtesy of Squawka.

Joint-second in the assist rankings

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Despite notching up just 13 assists during his 89 top flight appearances for Palace, Bolasie is currently joint-second in the Premier League's set-up charts with four - some return from just eight starts for the Toffees.

In fact, the only player to trump him in this regard is Manchester City's £55million midfield talisman Kevin De Bruyne.

Most impressively, all four of Bolasie's assists have come in separate games, including a set-up in the 1-1 draw with the Citizens, so this haul is by no means flattering of his contribution. Courtesy of Whoscored.

Partnership with Lukaku

It always felt as if Everton would have to do something special to keep Romelu Lukaku motivated this season, after the Toffees' tribulations last term and the Belgian battering ram being linked with practically every major European club during the summer.

But his newfound attacking partnership with Bolasie certainly has Everton's star striker enjoying his football and producing the goods, currently second in the Premier League's scoring charts with seven goals.

Four of those were provided by the 27-year-old, making the Bolasie-to-Lukaku combo the most prolific throughout the division.

Bolasie's not only getting the best out of himself, but also Everton's most important player.