One of the things about trying to compare players is that there is no definitive "Max Scherzer like" group. You set a series of definitions that fit the player you are interested in and you see what you get. Some of the players might seem like great comparisons, others you might wonder if you should bother to include them at all. You could narrow down, of course, with even more conditions but then the dreaded small sample size really comes into play. The last thing you want to do is put yourself in a corner where you seem to be saying one player is going to follow exactly the career path of another. It's a balancing act.
Case in point, this fangraphs article. We both have limits based on our analysis. Because I was limited by when pitches thrown data is available I could only look at pitchers from 2002 on. He used IP instead so he could go before 2000 but because he's interested with performance through the mid-30s but using performance through age 29 as a qualifier he can't use the most recent examples. They wouldn't have thrown those age mid 30 years yet.
His list looks far more impressive and even if you remove Clemens and Maddux (Scherzer doesn't seem to be in their class) and Teddy Higuera (only in MLB system at age 26 - most likely threw a TON before then) you still get a more positive view of Max. Viola (32, 33), Appier (32, 33, 34), Guidry (32, 34, 35), Cone (32, 34, 35, 36) and Mussina (32, 33, 34, 37, 39) all had plenty of success in the period that I've just deemed a probable wasteland for Max Scherzer. Only Jose Rijo blew up.
So who's right? Well no one really. I can tell you why I like my comparison group better though.
There are some things - like how comparable are pitchers who threw these years in the late 80s through early 90s? The runs scored may be back down but the approches are different. Guys aren't looking to put the ball in play as much. Whether that's strikeouts or walks it means longer at bats. This isn't a strict pitch count workload thing, these guys in the past threw a lot more innings. But if guys would swing at more pitches outside the zone and make more contact and if you were less worried about the long ball... that could effect stress on the arm. I'm a lot more in favor of saying Max is like a recent guy who threw say 575 innings at age 28-30 or 26-28 than a guy 20 years ago who happened to hit the 200IP limit in the 27-29 age range specified.
Another issue is the fact that there only one guy here who started his career after 1991. Why do, out of the 10, five of them lump together in careers starting from 1984-1986 when a 29 year span is specified? This makes the group seem to be non-random and should lead to further investigation.
For example, you can explain part of the above issue by the strikes in '81 and '94. If you happened to be 27-29 during either of those periods it would be hard for you to make this list (I think only Maddux and Rijo fit that bill). So if you are thinking, shouldn't Glavine or Smoltz or etc be here? That's what happened. That could explain for the most part the late 70s gap, along with the early 90s one. The late 90s one takes a little more thinking - perhaps starting out in a steroid induced high-scoring era led to fewer high WAR or big IP seasons? You can find some reason I bet.
But this strike thing brings up what I consider a bigger problem. Out of the 10 guys on your list, 9 of them (well 6 really - Viola, Rijo and Higuera all had their arms die before the strike but that doesn't count against my theory) had a season where they didn't have to pitch as much in the middle of their careers. How much does that help an arm out?
You might poo-poo that idea (who are you, Madeline?) but chew on this fact. Out of the latest group of 4 300 game winners - all had that '94 strike season in their careers. Out of the group of 6 right before them - all had that '81 strike season in their careers. Coincidence? Perhaps*. But it would make sense to me that having a light workload could rejuvinate an arm. It certainly jives with what I see for myself in my analysis. Once that workload threshold has been met and you get into your 30s a good year is more likely to follow a year with a light workload than a heavy one. If your arm is done then your arm is done, but if it's healthy getting that light workload can keep it on track.
There are a couple of other examples as well that fit this line of thinking. Ryan Dempster was heavily used for a few years while young but managed to have a lot of early 30s success as a starter. He also saw a big drop in workload during his late 20s as he was a reliever during that time. Javy Vazquez spent the back end of his career ping-ponging between good years and mediocre ones. After the age of 25 the IP in years before the seasons with less than 100 ERA+ : 230.2, 215.2, 216.2, 219.1. The IP in the years before the seasons with 100+ ERA+ : 198, 202.2, 208.1, 157.1
Anyway this is a long-winded way of saying I like my comparison just fine and better than that fangraphs one. You can make your own decision. You can find any number of groups that Max Scherzer might fit in. Baseball Reference for example likes Matt Morris, Roy Halladay, and John Lackey the most. Don't dismiss any grouping, but don't buy into it either. Look at it, think about how you feel about it. Do your own tweaks. Then adjust your judgement if you feel necessary. We're all just guessing here so if you want to make Max out to be Mussina or Oswalt or Webb that's all ok. We'll just forget about it by the time it happens anyway.
*They also almost all began their careers in relative minima in terms of runs scored. Easier time pitching as a young arm + a light year in the middle of career could help with longevity as much as anything else. Someone do some work!