How times have changed.
Since making his debut in 2005, Merrett's position has transformed perhaps more than any other.
Sure, the boys at the back are still big - look at Ben Rutten and Darren Glass - but now they have to combine it with a running power never seen in their position before.
They still need strength and power, but full-backs now have to be fit enough to cope with the demands of the modern press.
Merrett is 196cm, 104kg, about to turn 27, has 113 games under his belt - most as a full-back - and is changing his game now more than ever.
"You think as the bookends it's all about power and speed but you just need to get up and down the ground so much," Merrett said.
"If I go to a school clinic I tell the kids just to run, become a marathon runner and you'll be right. You have to be able to cover the ground these days.
"That's why the game is becoming so professional and that's what makes our sport so special, you can't just specialise in one area, you've got to be strong, you've got to be fit, you've got to be quick, and you've got to be able to take contact."
Merrett describes himself as a "shocking" distance runner, but one who was a continual work in progress.
He said it was an element of his make-up that would never come at the expense of his greatest assets - power and speed off the mark.
Merrett was having a stellar 2011 and was arguably in All Australian form when he suffered stress fractures in his back mid-way through the season.
His first 10 games were outstanding, and he comfortably led the League in one-percenters, all while blanketing most of his opponents.
Despite the devastating blow that cost him the final 12 matches, he said one positive was the extra time to get his body right for next season.
This pre-season, training has included two weeks of altitude training in Arizona.
"Having the change-up overseas, with fresh facilities and fresh surroundings, it's definitely kept pre-season interesting and exciting, and I feel like I've got a great deal out of it," Merrett said.
"Being a big fella I'd conceded I wasn't going to do as much as the midfielders but I was able to do a full program over there and get the run in my legs."
The Lions' defensive cornerstone said the whole squad had opened the pre-season fit and firing.
"Last season we were doing a lot of penalties or push-ups if someone was late or the drills weren't up to scratch, but there hasn't been many push-ups going on this year," he said.
"The boys understand the level we have to train at, they understand how far we were behind the competition and I think the guys weren't happy with where we were sitting last year and want to improve.
"From 12 months ago it's a thousand times better feeling in the group."
Michael Whiting covers Brisbane Lions news for AFL.com.au. Follow him on Twitter: @mike_whiting
