You seem to be unable to put those numbers into context.
Put them into whatever context you wish. He piles up points and goals at a rate higher than anyone not named Mario or Wayne over those six years. Closer to Gretzky in points than the next closest player behind him.
In 1988, he was 4th in PPG behind Savard.
Eliminate Lemieux and Gretz from the equation. They are arguably the two best players of all time. That leaves Savard and Yzerman was on pace to win the Richard that year.
1988/89, he truly stands out from the pack, although Nichols did too which was a bit weird.
Nothing weird about it for Nichols. Gretzky joined the team. Yzerman was by himself.
In 1989/90, he is behind Messier in points and Hull in goals. Another great season but not on par with the peaks of McDavid, Crosby or Jagr.
He was the best player in the league not named Gretz/Mario. He was on a crap team otherwise he would've won the Hart trophy.
And how is that not on par with McDavid? Does McDavid win the scoring title every year? No he does not. And Yzerman scores goals at an extremely high rate... Bossy like production. Much better than Jagr or McDavid.
In 90/91, he is 7th in points and 7th in PPG.
In 91/92, he 7th in points and 9th in PPG
Yep. But they're still outstanding years. You don't need to be 1st every year. Jagr wasn't. Bossy wasn't. Lafleur wasn't. McDavid isn't. 91 is an off year and he still comes in 2nd in goals. In 92 four guys ahead of him are either Mario Lemieux, Wayne Gretzky or teammates of those guys...
From 88 to 90 he's the best player in the league. In the following three seasons he's merely awesome.
In 92/93, he is 4th in points and 5th in PPG.
Again, eliminate Gretz/Lemieux. He'd be 2nd.
From '88 to '90, he is the clear best player besides Wayne and Mario with a PPG of 1.72 (Nichols - 1.52, Savard - 1.48, Messier 1.46) and a GPG of 0.79 (Hull - 0.65, Lafontaine 0.64)
Then from '91 to '93, he is a Top 3/5 player.
Show me a player who's best in the league six straight years.
Even Lafleur didn't do that. McDavid isn't. Only Gretz/Lemieux have that kind of domination.
If we elimiate Gretzky, Yzerman is 2nd to Adam Oates for points in that period and 2nd to Brett Hull in goals. And those two were playing together...
McDavid and Crosby were top players from age 19 until age 28/29. Jagr was there for 7 seasons.
If Yzerman kept his age 22 - 24 pace up then, yes, he would be in their tier. His 88/89 season is a statistical anomaly.
McDavid and Crosby and even Jagr didn't score goals anywhere near the amount that Yzerman did. Jagr had Mario Lemieux feeding him pucks for a good chunk of his prime and he's on the cusp of generational as well.
Yzerman's injury in 94 slowed him down considerably. From then on he's not the same player. But over that six year period he's head and shoulders the best player in hockey - by a lot. He's not regarded nearly as highly as he should be. Part of the reason for that is that by the time he actually had a good team to play on his prime was over.
His combination of goals and points are insane. You have to go to Mike Bossy/Guy Lafleur to find that combination over that period of time. Lights out the best player in the game for three straight years and the best over a six year period. Please find me players who can do that with the goal production Yzerman had. The list will be very short and it will have generational players like Bobby Hull/Gordie Howe on it.
Eliminating Gretz and Lemieux:
1988-90
Most points and goals
1991-93
2nd most points to Oates, 2nd most goals to Hull (Hull and Oates just happen to be playing together)
That's insane production. Especially on those horribad teams.