In this week's Things we learned, we discover that Port has a hole in its midfield, the Saints can't run out games, Freo's rising ruck is a force, plus more round 13 lessons.

1. Port Adelaide needs to bolster its midfield

The Power's midfield hasn't been the same since Zak Butters went down with his ankle injury in round four, with Port missing the young gun's class, skill, speed and ball-winning. Butters is perhaps Port's most talented player and his absence has left a big hole, with the club hoping he will be back in coming weeks. Port's defeats in recent weeks at Adelaide Oval to the Western Bulldogs, and again on Thursday night to Geelong, showed some extra midfield muscle would be handy. Ollie Wines is in the sweet spot of his career, Travis Boak continues to perform at a very high level and Karl Amon has become a star, but without Butters and wingman Xavier Duursma (knee), the Power are a bit slimmer in the midfield than other flag contenders. It is easy to see why they are among the clubs who have shown interest in Essendon free agent Zach Merrett and last year also had a look at former Crow Brad Crouch. - Callum Twomey

2. The Saints can't run out games

This was the most dramatic example of the season, but St Kilda's inability to get through four quarters is alarming. The Saints were humiliated by the young Crows in the final term on Saturday night, losing contested ball by 21, the inside 50 count by 15, conceding 3.6 to 0.3, and ultimately the match with Riley Thilthorpe's spectacular late goal. The Saints were simply out on their feet early in the fourth quarter, like a punch-drunk boxer waiting for the knockout blow, just like they were earlier in the season against Essendon, Richmond and the Western Bulldogs. Brett Ratten called it "unacceptable", and things won't get an easier following the bye, with the Tigers, Lions and Power all waiting. - Michael Whiting

3. Big Darcy is in the top five ruckman in the League

You can now count on one hand the amount of AFL ruckmen who would be backed to outpoint Fremantle big man Sean Darcy. Max Gawn and Brodie Grundy, yes, and Nic Naitanui would still have his measure in the centre square. But beyond that, Darcy is now a formidable opponent for the rest of the competition. Six days after a hamstring scare, the 22-year-old dominated Gold Coast with 39 hit-outs and seven clearances. He converted a 50m set shot at a crucial time and had an impact around the ground with 17 disposals and five inside 50s. His season average of 30.17 hit-outs ranks No.4 in the AFL, and he has claims as one of the most improved players in the competition. A clean bill of health has paved the way for Darcy to thrive in 2021 and he could be the ace that drives a strong second half to the season for Freo. - Nathan Schmook

4. Yeo has dusted off his Superman cape

The importance of midfield bull Elliot Yeo was on full display in the final quarter of Sunday night's epic win at Optus Stadium, and it is clear the dual best and fairest is ready to explode again after his long battle with osteitis pubis. The Eagles' have managed Yeo in his comeback at AFL level, but he was able to spend the entire fourth quarter on the ground and was as critical as the Eagles' sharpshooting forwards in the epic win. He had 10 of his 20 disposals after three-quarter time, and seven of his eight clearances in the run home, pumping the ball inside 50 six times as the Eagles mowed down the back-to-back premiers. It was a statement quarter from the gun onballer, who rewarded the Eagles' patience over the past 12 months by putting his superman cape on. - Nathan Schmook

5. Kelly's signature a crucial cog in Giants' future

Obtaining Josh Kelly's signature on a contract renewal and making him a Greater Western Sydney player for life is getting more important with each week for the Giants. Kelly's stats against the Kangaroos on Sunday had to be seen to be believed as he almost single-handedly dragged his side over the line. The 26-year-old racked up a massive 39 possessions and kicked two goals as the Giants had to settle for a draw with North Melbourne. The restricted free agent has the option of an eight-year extension at GWS, but if he decides to leave then it could be a catastrophic blow to the club. - Jonathan Healy

6. Complacency could cost the Swans

Sydney was handed a kind fixture this season after finishing 16th with five wins last year. But rather than building their season on regularly beating the teams now below them, the Swans are 5-4 against the current bottom 10. They were able to give the Magpies a five-goal headstart before overrunning them a few weeks ago but couldn’t rein in another cellar dweller, Hawthorn, this weekend. After a bye the Swans have three matches against top-four contenders then a clash with crosstown rival Greater Western Sydney. But a run home with games against Fremantle, Essendon, St Kilda, North Melbourne and Gold Coast could decide whether or not the Swans will be playing in September. - Martin Pegan

7. Melbourne's defence can be beaten

The first half of the season has seen Melbourne's backline rightfully lauded for its strong intercept work, particularly by Steven May and Jake Lever, while Christian Salem has dictated play off half-back. But Collingwood's relatively unheralded forward line was able to take advantage of some smart, controlled passing from further afield. The likes of Jordan De Goey, Jack Crisp and Scott Pendlebury were excellent in their decision-making sending the ball low and strong into attack, lessening the risk of being beaten in the air. - Sarah Black