IN THIS week's Nine Things We Learned, we discover that Collingwood has developed a crucial advantage over its rivals, a couple of flag greats aren't done yet, and an unsung Cat has become a key part of the AFL's best team.

Check out these lessons and more as our team runs their eyes over round 21. 

1. The Magpies are the mid-season masters

Collingwood's run of hot form is built on a number of factors but there's been a bonus come to fruition in recent times: a boon of mid-season rookie draft wins. On Friday night, in the Magpies' come-from-behind win over Melbourne, their first mid-season pick from last year, Ash Johnson, starred with four goals. His exhibition of quality inside 50 included the match-winning set shot and he has now booted 10 goals in his first four games at the top level. Josh Carmichael, the Pies' mid-season selection this year, has also settled in beautifully at the top level and brought something different to Collingwood's mix and he had 17 disposals against the Demons. Of course, the Magpies' first mid-season recruit since its reintroduction was John Noble, who is enjoying a career-best year, while the club has high hopes for ruckman Aiden Begg, also selected in 2021. - Callum Twomey

2. Cotchin can play on in 2023

The former Richmond skipper has been in vintage touch of late, but is out of contract at the end of the season. A three-time premiership captain can probably write their own end to their career, but the form and hunger Cotchin has shown – particularly against Port Adelaide on Saturday night – should mean there are few qualms about going around again if he wants. Cotchin had 31 disposals, 19 pressure acts, 17 contested possessions and six tackles against the Power, and is now averaging 25.5 disposals in the month since returning from a broken collarbone. - Sarah Black

3. JK is the most loved player of this Eagles era

You either believe players bring the same effort regardless of the occasion, or you subscribe to the theory that there is something extra in reserve that can be drawn upon when the moment demands. Sunday at Optus Stadium was all about Josh Kennedy, and his teammates – and the fans – found something extra in an attempt to send him off in the right way. Regardless of the final result, the Eagles' effort was at a level rarely seen this season. The crowd of more than 50,000 was the biggest they've played in front of this year. Nic Naitanui might be the king of the kids, and there are plenty of other Eagles who the fans are drawn to. But none have inspired the level of adoration Kennedy has. It was on show all around him in his farewell game. - Nathan Schmook

4. Brisbane needs its Magician to go all the way

Dayne Zorko was hindered by a plantar fascia injury at the start of the year and more recently a hamstring problem. The result has been an inconsistent season for Brisbane's captain and five-time best and fairest winner. Against Carlton though, 'the Magician' was back to his absolute best. His energy is infectious for his teammates, while his quick decision-making with the ball is often the catalyst to launch scoring chains. He finished with 22 disposals, nine score involvements and one clever goal. He appeared to have confidence in his body again, and needs to be at his best over the final six weeks of the season for Brisbane to push towards a premiership. - Michael Whiting

THE RUN HOME Five teams, three spots. Who'll miss top four?

5. The gulf between Essendon's best and worst remains cavernous

Ben Rutten desperately needs to figure out how to narrow the gulf between Essendon's best and worst. Essendon's best is spectacular, highlighted by the fact it was one straight Jamie Elliott kick away from five straight wins. But its worst is very bad, as shown by the 2-10 start to the season along with Saturday's "poor" showing against lowly GWS. The Dons offered little with Zach Merrett, who had been their leading ball-winner in the past four games, shut down by Harry Perryman, while their ball movement was uninspired with Mason Redman and Nick Hind's dash off half-back quelled. - Ben Somerford

6. Running machine Holmes has quietly become a key Cat

He's the unsung hero of Geelong's midfield who keeps on, but with a number of Geelong's stars missing, it was Max Holmes who made the most of his chance in the spotlight. The hard-running winger has slowly solidified his spot in the Cats' best side as of late and his eye-catching run continued in their 45-point win over the Saints, putting together a career-best showing at GMHBA Stadium. When everyone was tiring late in the game, Holmes was only getting started and his gut-running was on full show as the contest came to an end, especially as the Cats put the finishing touches on the victory. Holmes ended the night with 24 disposals, six marks, a game-high 531 metres gained, while capping his night off with a goal. Along with Isaac Smith, the duo are quietly forging one of the League's most imposing wing tandems which are starting to hit full stride at the perfect time of the year. - Nick D'Urbano

7. Contract talk is no distraction for ball-magnet Dunkley

With only two rounds to go in the home and away season, Josh Dunkley is still yet to put pen to paper on a new deal at the Whitten Oval, but the speculation isn't impacting his output. The Western Bulldogs star followed up a strong fortnight with one of his best showings of the season on Saturday against the Dockers, amassing 33 disposals, 23 contested possessions, 10 score involvements – all game highs – and six clearances. While it was Fremantle's Rory Lobb, another star being courted by rival clubs, who generated the headlines, it might be Dunkley who collects three votes on Brownlow Medal night. - Josh Gabelich

8. There's hope for the Kangas

This year hasn't gone to plan for North, and they have been on the end of some sizeable defeats. However, there have been much better signs during the past five weeks. They failed to close out Collingwood in round 17 after leading for much of the match, then beat Richmond a week later. After two heavy losses to Hawthorn and Essendon respectively, the Roos took it up to the vastly superior Swans on Sunday and played better than the 18th-placed side. Their pressure and effort was hugely impressive; they just lacked some experience and polish. With Adelaide (away) and Gold Coast (at home) to come, North has a great opportunity to finish the season well, which would do wonders for the club ahead of 2023. If the Roos can nail their draft picks and perhaps pick up a quality experienced player during the trade period, they can attack the new season with a bit of optimism. - Trent Masenhelder

9. Gunston has plenty of years left 

The Hawks are well and truly into their rebuild phase, and veteran Jack Gunston is capable of being in it for the long haul. The 30-year-old appears to have plenty left in the tank, after his five-goal haul against Gold Coast – his second five-goal bag in three matches – and general influence in games as he roams the forward line. Gunston has been instrumental to the Hawks' late-season resurgence that has seen them win four of their past five matches. Hawthorn will be looking to an experienced Gunston to help take their young side high up the ladder once again. - Alison O'Connor