England captain Alastair Cook said his side had still to conquer some longstanding problems after Pakistan had derailed their quest to become the world's number one Test side.

Pakistan's emphatic 10-wicket win in the fourth Test at The Oval, a victory achieved with more than a day to spare, saw the tourists deservedly end the four-match series all square at 2-2.

In the process they ended England's immediate hopes of returning to the top of the world rankings for the first time since 2012 and prevented Cook's side from holding bilateral series trophies against all the other nine Test-playing nations.

Opening batsman Cook and number three Joe Root continued to rack up the runs, but the rest of England's specialist batsmen struggled against Pakistan.

Cook and Root scored a combined 935 at an average of 66.78 over the four Tests, whereas the equivalent tally for the other members of the top five -- Alex Hales, James Vince and Gary Ballance -- was 498 runs at 22.63.

"Consistently, we haven't scored enough runs at the top of the order," Cook said.

"It's great we've got strength in depth. But the majority of the time they should be putting the icing on the cake, not making the cake.

"It is frustrating. It's a big area we've got to keep working on -- and obviously, for us to take that next step, top-order first-innings runs are vital."

Ever since former captain Andrew Strauss retired four years ago, England have struggled to find a reliable partner at the top of the order for Cook, with Nottinghamshire's Hales the latest batsman to be given a chance to make the position his own.

"It's not easy," Cook said. "Until you get that score, it is a very hard place to be. But there is a hell of a lot of talent in the guys who are playing."

'No Yasir Shah'

Spin remains an issue too, with Moeen Ali's position as the lone specialist slow bowler in a five-man attack again under scrutiny.

The off-spinner's11 wickets in the Pakistan series came at an expensive average of 46.54 apiece and denied Cook the control he wanted in the field.

"With the spin, Mo has done a fantastic job for us since he came into the side as a batter who bowled a bit -- and he's had to share a lot of responsibility to do that as part of a five-man attack."

"He's not a Yasir Shah, and probably never will be," added Cook in a reference to the Pakistan leg-spinner, who took 10 wickets in the tourists' first Test win at Lord's and five for 71 in England's second innings across London at The Oval.

"But he continues to work incredibly hard at it - and he picks up vital wickets.

"It's an area of the game which we'll look at."

England's fallible close catching was another worry for Cook.

"We can't afford to drop as many catches as we have in this series if we want to bowl sides out on good wickets like this one here," he said.

But Cook said the team's problems at The Oval were a fair reflection of their overall standing as a side who now remain fourth in the world rankings.

"At the beginning of this game it was 'you can become number one, could do all this'," he said.

"Probably these four days (show) exactly where we are."

A bad Test for Hales was made worse when he was fined 15 percent of his match fee for confronting third umpire Joel Wilson following his controversial first-innings dismissal off a low catch.

Nottinghamshire and England team-mate Stuart Broad received a 20 percent fine for his Twitter comments on the topic.

"It's not ideal," he said of Hales's conduct. "In the heat of the moment... I'm sure he won't do that again."