If Alastair Cook wants to feel better about his batting form, he may want to steer clear of the latest ICC rankings. After the Lord's Test against Sri Lanka he has dropped to 19th while Kevin Pietersen, who spent one day of the match enjoying a beer in a hospitality box, has climbed above him to No. 18.

That is the same Pietersen who has been sacked by the ECB. Before the ICC get on the phone, it is worth a reminder that players obviously do not immediately drop out of the rankings the moment they are not selected, or retire (which Pietersen did not officially do), even if it is a board decision to end their careers. Still, it is a bit of kick in the teeth for Cook.

He would have given anything for one more wicket at Lord's on Monday evening, but it is not only wins that the England captain is desperate for. The headline figure is that his wait for a Test century, which would be No. 26 of his career, has now extended to 22 innings. His previous three figure score came against New Zealand, at Headingley, so perhaps that is a good omen for Cook as he heads north to the same venue for the second Test against Sri Lanka.

Asked about his form after Lord's, Cook said: "I'd love a score. Leading from the front as a captain, you want to score runs - that's your job as a batter. The longer it goes on, the harder it gets."

Cook's lack of contributions did not stop England posting their highest total since playing India at The Oval in 2011 but his predecessor as captain, Andrew Strauss, knows how important it is for Cook to break the sequence he is in before it overshadows the team's performance and affects his captaincy.

"It really distracted me that I had become the story," Strauss told the Evening Standard. "It did affect my captaincy and I lost a bit of confidence, because I felt I was letting the team down. No captain wants to be a passenger in the side. You want to show the team the way forward.

"When I became captain in 2009, I scored a lot of runs but towards the end, perhaps I didn't have enough time to work on my batting as I was always thinking about the captaincy."

Since the start of the home Ashes almost a year ago, he has averaged 25.81 so his Lord's performance encapsulated his run: scores of 17 in the first innings and 28 in the second. On the first day he dragged a cut shot into his stumps and on the fourth, edged behind against Shaminda Eranga, after showing signs of more fluency, a familiar mode of dismissal which was a regular feature against Ryan Harris and Mitchell Johnson during the back-to-back Ashes.

It is a different run that he suffered in 2010 when his place in the side was briefly questioned after 106 runs in eight innings against Bangladesh and Pakistan. During that stretch he looked so horribly out of form that losing his off stump or edging behind off Mohammad Amir and Mohammad Asif felt inevitable. An ugly hundred at The Oval halted the slide and a few months later he embarked on what would become a record-breaking 2010-11 Ashes.

This time Cook is making starts - he has scored six half-centuries in those 22 innings - and has spent considerable time at the crease which on the one hand is a credit to his capacity to battle away but suggests the issues this time are as much mental as technical.

He has never had the most pure technique; the great strength during his glory years in 2010 and 2011 - and on his first tour as captain in India the following year - was his concentration at the crease. Over after over, session after session, day after day. Those reserves of energy now appear to be diminished, and that is despite a decent break from the end of the Australia tour to the start of the English season in April.

The question of whether it is the captaincy is the obvious one - he has had his fair share of issues to confront. The victorious series in India is often cited in Cook's defence in this case, and it still holds credence, but it is now a considerable time ago. Also, despite entering that series in the wake of the Pietersen reintegration Cook was still new and fresh to the Test captaincy. England also began that series with reasonably low expectations, which were even lower after defeat in the first Test.

Cook's run without a hundred during the ten Ashes Tests came against some outstanding pace bowling and in Australia, alongside the disintegration of the team. There are those who will argue that Cook's inability to arrest the slide - both personal and team-wise - was a sign of his own weaknesses, which is why this summer is so crucial to his longer term future.

With all due respect to Sri Lanka's attack, and what India will bring next month, a continued failure to recover something close to his best form will raise serious worries. Lord's was one Test out of seven England play over the next two months. There was much to be positive about by the new-look side, but runs for the captain are now top of the most-wanted list.