How reliable is ERA+ for evaluating pitchers with long careers?

[Bothrops Atrox]

I am introducing some more progressive thoughs on pitching to my father-in-law who is a pure traditionalist. He understands and likes ERA+, but thinks DIPS is a bunch of crap. Trying to find some middle ground, I am keying in on ERA+-about as far saber as he will get (well, I did convince him that OB% is better than average too). I felt comfortable telling him that to evaluate a pitcher with a long career, take their ERA+ and adjust it a few points up or down depending on the quality of defenses they played on. Is this in fact a pretty accurate way of producing a quick and quality snapshot of a pitcher's career ability to prevent runs? Here is what I am thinking:

If park factors are included in ERA+ (brett's adjustments instead of BBR's if you wish), and if hit luck evens out over the course of a long career, aren't leveraging and defensive support the only factors that could significantly distort a long-tenured pitcher's ERA+? I know that ERA+ from season to season is not a great indicator of ability due to luck factors, but as long as a pitcher didn't get the Jim Palmer treatment (great defensed behind him for 15 years) or the Juan Marichal treatment (never had to face his offense that created 18% more runs per season than average), then a guy's ERA+ with 3,000 + IP would be pretty close to his "true talent ability", right? I am assuming that guys similar to Palmer would have to play with incredible defenses for long periods of time to significanty adjust their ERA+s. I have estimated recently that the defenses behind Greg Maddux only added about 2 ERA+ points. Hardly significant enough to claim that his ERA+ is not very accurate. Much has been made about Grove's usage pattern during a few of his peak seasons, but that alleged treatement only appears to have a 1-2 point ERA+ adjustment on his career. Not enough to greatly change his overall status, in my opinion.

[BlueBlood]

I think that's a solid foundation. I mean, unless someone were a complete nitpicker who thinks that 1-2 or points of ERA+ over a career matter greatly in ranking all-time pitchers it really doesn't seem to matter.

[Pere]

as long as a pitcher didn't get the Jim Palmer treatment (great defensed behind him for 15 years) or the Juan Marichal treatment (never had to face his offense that created 18% more runs per season than average)

But that could be a pretty significant difference, no? Wouldn't you think the variance in defensive and offensive quality of teams is often larger than the variance in park effects between two pitchers?

[Bothrops Atrox]

But that could be a pretty significant difference, no? Wouldn't you think the variance in defensive and offensive quality of teams is often larger than the variance in park effects between two pitchers?

Absolutely, but I don't think there are many big inning pitchers post WW2 that have had so much help from their defenses and/or leveraging that their career ERA+ would be ajdusted to the point of drasticaly changing their percieved "ability" level. Palmer is one exception. How many other pitchers in the past 40 played 12+ years with awsome defenses? Everybody says Maddux, but from 1986-1992 and 2004-2006, he pitched in front of mediocre defenses. During his Braves stint, sure, the Braves' defense was great in 1993and 2002, and very good in 1997, 1998, and 2001, but they were quite pedestrain in 1994-1996 and 1999-2000. Was he helped by his defense? Of course, they probably saved him about 35 runs or so during those 5-6 years top years, but that would only change his ERA+ from 135 to 133. Not too big of a deal. Therefore, if I referenced ERA+ in regards to Maddux' actual quality, I do not think I would be wrong for doing so.

I also estimate that Gibson woul lose about 3 ERA+ points (but those are made up almost entirely by his own offensive contributions), Glavine would lose 3 ERA+ points (again two of those would be made up by his own offensive production), and Spahn about 3 as well - again with most of that being made up by his own offensive production. I am sure Whitey Ford would lose several, but when your ERA+ is 130, losing 2-3 ERA+ points isn't so devastating. I feel that with these guys, I could still look at their career ERA+ and get a pretty accurate idea of how good they were. I estimate Palmer would lose 5-6 points, so he is the exception.

[KCGHOST]

It is much superior to regular ERA so it has substantial merit when measuring pitchers. Like all of these stats though it is not without its weaknesses.

[Paul Wendt]

park factors for pitchers and batters

If park factors are included in ERA+ (brett's adjustments instead of BBR's if you wish), and if hit luck evens out over the course of a long career, aren't leveraging and defensive support the only factors that could significantly distort a long-tenured pitcher's ERA+? I know that ERA+ from season to season is not a great indicator of ability due to luck factors, but as long as a pitcher didn't get the Jim Palmer treatment (great defensed behind him for 15 years) or the Juan Marichal treatment (never had to face his offense that created 18% more runs per season than average)

I don't know the brett v BBR implementation but I know Palmer. Pete Palmer's team park factors PPF and BPF incorporate the quality of the team at bat (in PPF for pitchers) and in the field (in BPF for batters).