It feels like both Cristiano Ronaldo and Lionel Messi are in the autumn of their astonishing careers and yet they're the two favourites for this year's Ballon d'Or. Should either triumph again -- the smart money is on Ronaldo -- it will be nine consecutive years that these two have dominated the award, an incredible duopoly unlike anything football has previously witnessed.

A key part of their rivalry, of course, is that since 2009 they've been competing for rival teams in the same division. The Clasico has sometimes taken the form of a head-to-head battle between them: in October 2012, for example, Real drew 2-2 at the Camp Nou, with Messi and Ronaldo scoring two goals each. They've come to define their clubs in very different manners: Messi is seen as the neat, intricate team player and Ronaldo the powerful, athletic individualist.

Those caricatures have remained consistent throughout their seven-and-a-half-year spell in La Liga, but it's notable that their precise style and tactical deployment has changed considerably.

During their first season together in Spain, Ronaldo played almost exclusively on the flank, while Messi was pushed inside to take up the false nine position that would eventually become regarded as his permanent home. Their tactical evolution over the past couple of seasons has been completely different, which is summarised neatly by relevant statistics regarding their contribution with the ball.

Taking four basic metrics -- shots per game, pass completion rate, chances created per game and dribbles per game -- tells us a very interesting story.

Shooting

The headline here is that Messi's shooting figures have remained largely consistent, but there are a couple of interesting features. First, his lowest shots-per-game rate came in 2010-11 (4.5) but was at its highest the following year (5.5). Since then, there's been a steady decline (5.1, 5.0, 4.9, 4.9, 4.8) that accurately follows Messi's role in the side: the 2010-11 campaign was his purest "false nine" season. Then he became a record-breaking goal scorer, hitting 50 goals in 2011-12, and has gradually dropped back into a deeper, slightly more reserved role.

Ronaldo has experienced something extremely similar. His peak was also 2010-11 -- an incredible 7.4 shots per game -- but since then it's declined: 6.9 (2011-12), 6.9 (2012-13), 7.2 (2013-14), 6.4 (2014-15), 6.3 (2015-16), 6.2 (2016-17). It's notable, though, that this doesn't really reflect Ronaldo's changing role: he's become more of a "final third" player yet he's not shooting as much. This seems more a reflection of his declined powers rather than his positioning.

Pass completion rate

Fascinatingly, Messi's pass completion rate has dropped slightly but very steadily over time. From 86 percent in 2009-10 and 2010-11, it's since been 84 percent (2011-12), 85 percent (2012-13), 85 percent (2013-14), 83 percent (2014-15), 82 percent (2015-16) and, so far this season, 80 percent. This seems to correlate nicely with Barcelona's changes rather than his own: tiki-taka under Pep Guardiola has given way to a slightly more purposeful, direct approach in possession in recent years.

Ronaldo's figures here have jumped around more, ranging from 76 percent to 84 percent, but it's notable that the final figure is for this season. Never before has Ronaldo been so successful with so many of his passes. Again, this doesn't seem to tally with him becoming more of a penalty box player.

Key passes

Looking at key passes -- essentially a "shot assist" -- is an interesting factor because both players are averaging unusually poor returns this season. Messi is usually up at around the 2.4 mark, although this season it's at 1.6, the second-lowest figure during the Ronaldo-Messi era of La Liga. This may, however, simply be because of a small sample size.

Ronaldo's figures have jumped around over his seven and a half years in La Liga, but it's notable that his highest rate of creating chances for teammates was in his first season (2.6) and his lowest rate is this season (1.2). Again, a small sample size might be a partial cause, but considering that last season's figure of 1.4 also marked a notable decline, it seems obvious that Ronaldo is no longer a great provider.

Dribbles

Again, there's a steady decline here for both players. Messi was taking the ball past opponents 5.6 times a game during his peak 2010-11 season as the "false nine," but last season that figure was just 3.5 times per game and this season it's down to 3.0. That decline is slightly surprising considering Messi is now stationed on the wing, finding more space and often in situations where beating opponents is much easier. This probably points to a slight loss of acceleration over the first couple of yards (previously Messi's trademark), although 3.0 dribbles per game is still very high.

Ronaldo's decline is even more dramatic. When Ronaldo arrived at the Bernabeu, he was beating opponents 3.1 times per game; it has been under 1.5 for the past couple of seasons and is now down at 0.7, a very low level in the context of his career.

Summary

Messi's stats have declined significantly in terms of pass completion rate and dribbles, and there's also a slight -- but perhaps not yet significant -- drop in terms of key passes. What's notable, though, is that his shots figure has broadly remained consistent over the past five seasons. Even in his different role with a little less dynamism, Messi remains an extraordinary goal-scoring threat when cutting inside and shooting from a wide role.

Ronaldo's decline, however, seems more complete: his numbers are down noticeably in terms of shots, key passes and particularly dribbles, although it will be interesting to see whether this year's high pass completion rate continues.

Might Ronaldo reinvent himself as not simply a penalty box finisher but also as a clever centre-forward who helps build attacks? If so, with Messi concentrating on shooting from a wide role and Ronaldo improving in terms of his link play from a centre-forward position, we might be seeing a quite extraordinary role reversal from the world's two dominant talents.