The real leap forward that Charlie Chaplin made in screen comedy, the thing that put him ahead of his peers, was that he staged his comedy within a straight and serious world. His first two Keystone pictures had little plot but allowed his little tramp to interact (chaotically) with a realistic environment, albeit with a handful of supporting comedy characters thrown in. With the Champion he moved on to develop stronger story lines which were not funny in themselves, but which gave the tramp a world to be funny in.
The set-up of an up-and-coming boxer who fights his way to the top, is then bribed into throwing a fight and has to choose between his integrity and the payoff was an established cliché even back then. This well-known sequence of events allows Chaplin to mess around with stereotypes or subvert conventions. For a start, there is the fact that Charlie is a scrawny little feller, who essentially cheats his way to the championship. Then there's the farcical training routine, which Chaplin cross-cuts with the opponents more serious routine to give it more comedy impact, followed by the tramp's nonchalant seeing-off of Leo White's over-the-top sinister villain.
Throughout Chaplin is showing more confidence in his staging and arrangements. He allows himself to become a more marginal figure in some sequences – for example when Spike Duggan is knocking out one challenger after another, Charlie isn't doing very much, and is off-screen half the time, but it's his reactions to the growing number of defeated men that is funny. The other characters simply act naturally, whereas Chaplin is the originator of all the comedy.
In Chaplin's previous picture, A Night Out, he came dangerously close to becoming a double-act with Essanay's resident comic Ben Turpin. A large part of Chaplin's humour was based on reacting to other comedy characters, so he needed to have his supporting cast of burly bullies and pompous twerps to antagonise. However in the Champion you can see he is being careful not to let any of them have too much screen time. Although Bud Jamison, Leo White and Ernest van Pelt all do a great job, each of them is a walk-on, walk-off character; none of them shares the picture with Charlie. Ben Turpin has a tiny part as a vendor, but even in this one-shot role he manages to violate Chaplin's rule of the tramp being at the comedic centre of attention, stealing the laughs as he scrambles over the crowd to reach a customer. This would be Turpin's last picture with Chaplin.
And now, we finish with the all-important statistic – Number of kicks up the arse: 1 (1 for, 0 against)