India v England: Alastair Cook may not decide his future - Agnew

Joe Root (left) has been England's Test vice-captain and Cook's heir apparent since May 2015

England's collapse on the final afternoon of the fifth Test is one of the worst I have seen - and I have witnessed a few.

The Test was as good as saved. Needing to bat through the day, England had all 10 wickets in hand at lunch and were 103-0 soon after.

That they ended 207 all out, losing by an innings and 75 runs, was gut-wrenching. It rendered all the talk of fight, spirit and character that we have heard from within the camp as worthless.

Was it Alastair Cook's fault that England lost in that way? Absolutely not. He actually batted very nicely to get England through the morning session, only to be let down by the majority of team.

However, when you have presided over something so cataclysmic in sport terms as that, then it is only natural that both Cook and the powers that be in English cricket may be thinking differently about his future as captain than they were at the start of the match.

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Going back to how the speculation about Cook's future began - a story at the start of the tour where he said he was looking forward to not being captain - I believe he simply gave an honest answer to a question he was asked.

The truth is that England do not appoint captains forever.

Cook and director of cricket Andrew Strauss do meet for debriefs at the end of every series. The captaincy is regularly reviewed.

However, Cook's candid comments gained more attention because it was quite widely known that he was nearer the end of his tenure than the beginning.

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Before this final-Test defeat, it was quite likely Cook's future was largely in his own hands.

I still suspect part of the England hierarchy will want him to stay on for next winter's Ashes series, but it might also be that the likes of Strauss and the rest of the management team feel they have to draw the line now.

As for Cook, if he was feeling bullish about his future as skipper, he may not be any longer.

He is probably coming to the realisation the decision on the captaincy may not be as much in his hands as he thought.

Indeed, everyone involved could reach the conclusion it is the right time to make a change, so that new energy, focus and direction is brought to the job. There is sense in that.

If Cook either resigns or is sacked, then the players in his team must share the responsibility.

I have said previously that, even although England were expected to lose this series, we wanted to see improvement in individual players who were leaving with new skills that would have made the trip worthwhile.

When you see a collapse like the one in Chennai, you wonder how much has been learned.

In that respect Moeen Ali, as just one example, will have the finger pointed at him for an awful stroke that began England's ultimate demise.

With runs not even in the equation, he skipped down the pitch at Ravindra Jadeja and was caught at mid-on.

It was completely reckless, and beyond me to explain what he was trying to achieve.

That is not a personal attack on Moeen, but merely an example that highlights how England have not just failed to take their chances, they have actually given them away.

We knew how difficult this assignment would be. Seven back-to-back Tests in Bangladesh and India is the hardest tour England have ever had; it has been relentless.

We also knew England would probably lose, mainly because their spinners are not of the same quality as India's.

But that does not excuse the familiar batting collapses or the regular missed chances in the field. Again, the blame for those cannot all be laid at Cook's door.

And so we wait for a decision on his future. There are three one-day internationals and three Twenty20s after Christmas, but they are not likely to deflect attention from speculation over the biggest job in English cricket.

If Cook does go, Joe Root is the natural candidate to replace him. At 25, it may be a year earlier than England would have liked him to take the job, but he has risen to every challenge put in front of him so far.

Whatever happens, Cook will remain the object of a tremendous amount of goodwill and respect. I doubt there would be any problems with him returning to the ranks.

England will want him to score lots of runs for a number of years to come and I would expect him to do just that.

Jonathan Agnew was talking to BBC Sport's Stephan Shemilt