I've seen too many teams fail over the years due to inability to close out games to think it's not important. Rivera turned it into an eight inning game.
I understand the argument against closers. I get the logic. I just think it's silly.
Here is a large part of my problem:
Here are the relievers with 300+ saves who also spent time as a starter and their stats as a starter (Excluding Eckersley because he is a completely different case than most of them being a 10 year starter and Goose Gossage because he randomly started for one year 5 years into his career)
Mariano Rivera - 10 starts. 5.94 ERA. 50 innings. 20 walks. 38 strikeouts
Joe Nathan - 29 starts. 4.60 ERA. 162.1 innings. 96 walks. 95 strikeouts
John Wetteland - 17 starts. 5.49 ERA. 82 innings. 31 walks. 74 strikeouts
Jose Mesa - 95 starts. 5.07 ERA. 564.2 innings. 232 walks. 285 strikeouts
Rick Aguilera - 89 starts. 4.08 ERA. 551 innings. 135 walks. 379 strikeouts.
Jason Isringhausen - 52 starts. 4.66 ERA. 319 innings. 142 walks. 217 strikeouts.
That's the whole list and they all range from bad to horrible. So I'm not saying closing isn't valuable (hey, I like that the Mets got Edwin Diaz) but I have a real problem with voting for guys like this for the hall of fame since when they pitched in a tougher role they more pretty much universally awful. Rather elect their manager to the hall of fame for deciding to move the player to the bullpen. If these guys could be terrible and still be in the 300+ save group how many other terrible starters could do something similar (not necessarily as dominant as Rivera though)
It's the same thing if you look at recent pitchers too. Here's the top 10 relievers in ERA the last 5 years 100+ innings
1. Zach Britton - a bust as a starter
2. Chad Green - pretty good starter in the minors. hasn't had much of a MLB opportunity
3. Richard Bleier - bad minor league starter
4. Andrew Miller - bust as a starter after being drafted 6th ovr
5. Wade Davis - bust as a starter
6. Chapman - surprisingly he never wanted to start so who knows
7. Carson Smith - reliever his whole career
8. Dellin Betances - a bust as a starter in the minors/moved to the pen
9. Kenley Jansen - reliever his whole career
10A. Craig Kimbrel- reliever his whole career
10B. Josh Hader - used as a multiinning reliever/could become a starter in the future if they want