Francesco Totti's Ageing Curve

40 year old Francesco Totti ended his 25 year association with AS Roma when he appeared for the final half hour of last weekend's game with Genoa.

Totti has played over 600 Serie A matches, clocking up over 47,000 minutes of playing time, while scoring 250 league goals, although 71 of those have come from 12 yards and over that period, Roma has enjoyed consistent success, rarely dropping out of the top four positions.

As league careers go, Totti's has therefore been played at a very similar level, where Roma has been regularly amongst the best club sides in Italy and he has largely avoided injury.

Between 1994-95 and 2014-15 he has played at least 1,000 minutes in each and every season, peaking in 2006-07 when he managed 3,034 on the field minutes.

As such he is an ideal subject to see where is performance levels stopped improving and began that inevitable, age related decline, albeit from a very high level.

Quantifying the performance achieved by a players over the course of their careers is problematical. Playing time can often be used as a proxy, but goal output is perhaps the most easily accessible benchmark for an attacking player's current and previous level of play.

Here's the, inevitably noisy plot of how Totti's non penalty goals per 90 have changed from one season to the next over his long career.

The trend line indicates that improvement is replaced by decline when the horizontal axis is breached by the trend and this occurred when Totti was just over 28 & 1/2.

This doesn't of course mean that he suddenly because a poor player, merely that his best years, on average and from a scoring perspective were most likely behind him. Although as he subsequently demonstrated, he was still capable of contributing to Roma, perhaps in a slightly different role.

So footballers are all prey to ageing, although some have such high levels of innate talent that they can, like Totti prolong their time spent at the highest level because their aged talents are still above those peak years of less talented contemporaries.

Which brings us to tonight's champions League final, featuring Ronaldo. A player who has had a more varied league career, spanning Portugal, England and Spain, but judged against his own highest standards, has been himself in decline since just prior to his 28th birthday.