Let's remember that Doug Gilmour in like 3 years left a much deeper mark in the Toronto fanbase's subconscious than Sundin did in 15 years.
Sundin was a legit #1 center, but he was a bit of a compiler too.
Leafs fans like good old Canadian boys like Doug Gilmour and Wendel Clark. Doug Gilmour's great peak happened before I was born but there's no question he is thought of fondly by Leafs fans because of it. Mats was traded for Wendel and came in overshadowed by what Gilmour had done in the years prior. You also had Don Cherry running his mouth and degrading Swedes. There's Leafs fans that prefer Clark to Sundin as well but that doesn't take away from Sundin's greatness as a player. There's no question that Gilmour is highly respected for what he did, but Mats is highly respected as well, particularly by my generation of fans.
The compiler comment is way off.
Mats played 18 seasons which is definitely a good run but many Hall of Famers played 20+. Of those 18 seasons there were only 3 in which he didn't score 70+ points: his 59 point rookie season, the 94-95 lockout-shortened season in which he scored 47 points in 47 games, and his final season which he jumped in at the half-way mark and still managed 28 points in 41 games as a 37 year old. He produced at a high rate all those years and barely missed any games. That kind of consistency is remarkable. To say he was only a top 10 scorer twice in his career is leaving out a huge party of the story because as others have pointed out, he was consistently just outside of the top 10.
However, I don't think looking at points is the best way to judge Mats. Those who watched him play know how important he was to the Leafs; without him the Leafs wouldn't have been making the playoffs as often as they did, nevermind going on any deep runs. He certainly would have piled up more points being surrounded by more talent.
I feel goals are a much more effective way of assessing his impact considering he likely would have far more assists had he been surrounded with more finishers.
Mats is 8th all-time in goals among centers
Mats was 5th in goals among centers during the first half of his career (1990-91 to 1998-99)
Mats was 2nd in goals among centers during the last half of his career (1998-99 to 2008-2009)
Mats was 1st among centers in goals during his Leafs tenure (1994-95 to 2007-08)
Sundin's offensive ranks among all skaters during his 13 year Leafs tenure (1994-95 to 2007-08):
Goals: 5th
Assists: 6th
Points: 3rd (behind only Jagr and Sakic)
Even Strength Goals: 3rd
Even Strength Points: 3rd
Power Play Goals: 8th
Power Play Points: 10th
Shorthanded Goals: 6th
Shorthanded Points: 7th
Game Winning Goals: 3rd
I get that he may not have the incredible peak season with eye-popping numbers like many Hall of Famers do but his consistency adds up to high-rankings over a longer stretch of time. Check out his International resume if you want to see his peak numbers and the accolades to go along with it.
I do think the conversation around Mats would be very different had he won and/or been surrounded by more talent. But what he managed to do under the circumstances he was placed in playing in a market as difficult as Toronto was incredible. Maybe he didn't win the cup, but the value of a franchise center who doesn't have down years and rarely gets hurt has towards winning shouldn't be understated. It was a matter of surrounding him with the right players, but Mats did his part in bringing a winning ingredient to the table each and every year.