The function of a closer was quite different in those days (i.e. the 80s).
Closers used to be workhorses.
In Sutter’s top year for saves (1984 when he saved 45), he appeared in 71 games and pitched 122 innings.
In Mariano Rivera’s top year for saves (2004, 53 saves) he appeared in 74 games and pitched 78 and 2/3 innings.
Sutter in 1984 had six games with 3+ innings pitched, and another 35 games with at least 2.0 IP.
Rivera in 2004 had five games with 2.0 IP (never had more than that).
Rivera faced 10 or more batters on two occasions (11 and 10 were his top two marks) in 2004.
Sutter faced 10 or more batters 13x in 1984 (with top marks of 15 and 14).
The emergence of the middle reliever over the past 15+ years has made it possible to make a career out of pitching one inning at a time every couple of days.
Now don’t get me wrong, I’m not saying Sutter was better than Rivera or anything like that. But if Sutter only had to pitch an inning at a time throughout his career, his save numbers would probably be substantially higher.
And Sutter really was tough to hit. When most of us first heard about a “split fingered fastball” (as they used to call the splitter), it was Sutter who brought that pitch to the game.
Sutter also won a Cy Young award (1979 NL) at a time when relievers didn’t get nearly the respect that they do now. Only Mike Marshall (1974 NL) and Sparky Lyle (1977 AL) had won the award prior to that as relievers.
Sutter is a worthy HOFer. But like a lot of great HR hitters of that era, his career totals don’t necessarily look so great compared to today’s top career relievers who, as I mentioned earlier, built a career one inning per game at a time.
Finally, I would not exactly say that Sutter got into the HOF easily. His first year on the ballot was 1994, and he was under 30% of the vote for the first four years of eligibility.
He was finally elected in his 13th year of eligibility with “only” 76.9% of the vote (75% needed for induction).