He doesn't have Nat Fyfe's size or marking prowess. He isn't as explosive or powerful as Paddy Dangerfield. He doesn't kick goals like Buddy Franklin or accumulate, accelerate and dominate in the manner of Gary Ablett. He can't make the earth stand still like Scott Pendlebury.

He's a  solid six foot (183cm), some centimetres shy of the template for the superstar modern midfielder and his versatility isn't as obvious as those larger rivals.

But, as of round four 2015, Joel Selwood is the game's most influential player. To be deemed the most influential, or the most valuable player, is not quite the same as being rated "the best". Leigh Matthews  defined the "ultimate" test of a player's worth by posing this question: "How much do you contribute to your team's success?"

No contemporary player is contributing more to his team's chances of winning than Selwood. This is more apparent in 2015, when the Cats have slipped from contention, and their reliance upon the captain has been laid bare – most dramatically when Selwood picked up an injury-ravaged and almost beaten team – as if it was a sack filled with rocks and dragged them over the line last Sunday against the Suns.

The case for Selwood as the AFL's MVP is entirely subjective, but based upon Matthews' maxim about team success. If you base a footballer's worth purely on statistics, Selwood won't be your man. Not quite. It's the less easily measured qualities – leadership, inspiration – combined with his enormous football output than puts the Geelong captain a cigarette paper ahead of the formidable Fyfe, Buddy and the others for influence.

What about Ablett? Well, he's  phenomenal footballer, probably the "best" of his generation. Most of those within the game I surveyed still placed Gazza at the head of the heap. But he's hurt and even when he returns, I doubt the nearly 31-year-old champ will exert as much influence on his team as Selwood does on the Cats. Selwood is 26, at his absolute zenith and has a more obvious galvanising impact on the team. He is the more natural leader.

Selwood's most defining trait isn't what he does, but WHEN he does it. Last Sunday, more than a million viewers saw him intervene – particularly in the decisive third quarter – as the Cats were about to disappear down the plughole. During that momentum-changing third term, Selwood had 11 of his 38 disposals, seven contested balls, five clearances and a goal.

Last year, when the Cats struggled to overcome the Blues and Selwood was relatively quiet, he burst clear from a stoppage to boot the match-winning goal from 50metres with about a minute remaining. In so many of Geelong's close victories, he's the catalyst for reversing the momentum. "When they're in trouble, he seems to spark the revival," said Matthews.

Like Luke Hodge, Selwood's influence is elevated by his leadership and his capacity for desperate acts that inspire teammates. But whereas Hodge is more of a "director" of Hawthorn's match-day production, Selwood is the lead "actor" or what Matthews calls "a doer". Hodge spends more time cajoling, coaching and using his hands to direct teammates. That the Hawthorn skipper usually plays a step behind the ball suits this style of captaincy, because  it is harder to direct the troops when attacking the ball like a savage dog in a midfield cluster.

Selwood isn't lacking in athleticism. He had hurdling records as a youngster in Bendigo and is one of Geelong's best distance runners. Mark Blicavs, who was on the brink of OIympic steeplechasing before converting to footy, easily wins the two or three kilometre runs, with either Selwood, Mitch Duncan or Josh Walker next. But, according to one who knows the skipper well, "Joel won't be beaten by Mitch or Josh twice."

Selwood doesn't accept defeat. It is the content of his character, rather than athletic traits, that have shaped his career. He has what a journalist friend would describe as unmatched "loss aversion". This refusal to countenance defeat is how he keeps chasing the ball when his legs can barely move, that he accelerates into the contest when required and that he has an innate capacity to summon an effort when the moment demands it.  Selwood-watchers from Geelong and elsewhere posit that his position in the family – as the third of four talented and tough brothers – has helped forge his will to win.

Some players are driven to succeed for themselves, and in their professionalism resemble a single-minded tennis player. Critics of Don Bradman viewed the cricketing colossus in that light. One could mount an argument that to be Tiger Woods, Roger Federer or Bradman requires obsessional self-focus.

In the AFL, however, the most influential players – eg Wayne Carey  – raise the performances and output of teammates. Typically, the most indispendable players fill key positions.

But elite players of any size who can galvanise and inspire teammates are as rare as super key position players. If Selwood's influence is most pronounced when the Cats are in an arm wrestle, or struggling, he has a particular knack for imposing himself in the centre square. This year, he's had 14 centre clearances (third in the competition), directly creating four goals, which is double the next best in the competition. Centre breaks are important in momentum shifting, more so because, in the new congested game, it gives the attacking team a rare chance to have equal numbers.

In the final quarter, as the Suns pressed and were within a kick, Selwood found himself in a contest on the wing, in apparent exhaustion, seemingly unable to lift his legs. He seemed spent. "But about 30 seconds later, he's down in the Geelong forward line with the ball," marvelled one long-serving official and ex-assistant coach.  No matter the situation, or the burden, Selwood never ceases.