Why is 4.5 game ERA so magical in terms of W/L?

[curious]

I had a bad beat the other day where a pitcher had great stats the last 3 games and then got blown out by the 2nd inning. So, I started looking more closely into the pitcher's record and he had very few starts that left his team in a position to win the game, so the record over the last 3 games was an anomaly.

I added another dimension to my capping to keep that from happening again. I list the # of Games Started, the number of Good Starts, and the number of Bad Starts. While researching what might be a "Good" start, I looked at the Quality Start stat that some like to use. They use a game ERA of 4.5. I don't like the way they do that stat, but I wanted to look into this ERA of 4.5 because I thought "why 4.5? why not 2 or 8 or 3 or 6"?

I started running queries that show what a team does when a starting pitcher has a game ERA above or below 4.5. The results are pretty astonishing. The records aren't even close.

If the game ERA is <= 4.5 pretty much the team wins the game. The % varies by pitcher and team but it is between 70% and 90%.

If the game ERA is > 4.5 then pretty much the team loses the game. The % again varies by team and pitcher but it is again between 70% and 90%.

I find this extremely intriguing that there is a number at which above and below the Win/Loss result is so drastically opposite.

[homerbush]

Keep in mind that Quality start does not equal 4.50 ERA exactly. Example, 8 innings of 4 Earned Run ball would be an ERA of 4.50 but it does not qualify as a Quality Start. So keep in mind that ERA of 4.50 or lower does not always equal a quality start when looking at quality starts.

[EXhoosier10]

By "game ERA is <= 4.5", you mean the pitcher's game ERA and not the ERA of the entire team, right?

[curious]

Keep in mind that Quality start does not equal 4.50 ERA exactly. Example, 8 innings of 4 Earned Run ball would be an ERA of 4.50 but it does not qualify as a Quality Start. So keep in mind that ERA of 4.50 or lower does not always equal a quality start when looking at quality starts.

Quality start is defined as 6 or more runs with 3 or less runs allowed. I took 3 runs in 6 innings to equal 4.5 ERA. Yes, I know that most games are not 4.5, most games either go more innings or have less runs scored.

but, I had to start somewhere.

And in the way I did it, I said a good start was starter runs / starter innings pitched less than or equal to .5. And a bad start is starter runs / starter innings pitched is greater than .5. Most of the games are more or less than 4.5 ERA.

In the stats that I ran 4.5 is definitely a dividing line. I can see why they use the 6 innings and 3 runs in their formula.

[curious]

By "game ERA is <= 4.5", you mean the pitcher's game ERA and not the ERA of the entire team, right?

yes, i use starter runs * 9 / starter innings pitched <= 4.5.

Bullpen runs is a whole different can of worms. But there is definitely a correlation that the team will win the game if the starter leaves the game with having given up fewer runs than a 4.5 ERA for the number of innings pitched. Regardless of what quality their bullpen is. Weird, I know.

[curious]

Quality start is defined as 6 or more runs with 3 or less runs allowed. I took 3 runs in 6 innings to equal 4.5 ERA. Yes, I know that most games are not 4.5, most games either go more innings or have less runs scored.

but, I had to start somewhere.

And in the way I did it, I said a good start was starter runs / starter innings pitched less than or equal to .5. And a bad start is starter runs / starter innings pitched is greater than .5. Most of the games are more or less than 4.5 ERA.

In the stats that I ran 4.5 is definitely a dividing line. I can see why they use the 6 innings and 3 runs in their formula.

This should say 6 or more innings ith 3 or less runs allowed. I wish Willee Bee would get off his ****ing high horse and give me my ****ing edit button back.

[curious]

Keep in mind that Quality start does not equal 4.50 ERA exactly. Example, 8 innings of 4 Earned Run ball would be an ERA of 4.50 but it does not qualify as a Quality Start. So keep in mind that ERA of 4.50 or lower does not always equal a quality start when looking at quality starts.

Sorry I didn't explain this right. I don't use he quality start stats. I just looked at their formula and used the 4.5 ERA in the formula I use.

I run my own queries to find what I call good starts and bad starts.

A good start is given by the query: starter runs*9/starter innings pitched <=4.5

A bad start is given by the query: starter runs*9/starter innings pitched >4.5

If I see a pitcher who has a high % of bad starts I either fade him or look at taking the over depending on the other starter, the umpire, weather, park factors, etc.

[InTheHole]

edit

[seanjohn007]

hey curious, havent seen you around in a while, how you been. its kinda funny to hear oyu say that because recently i started looking at pitching eras a little more. granted i dont have the computer programs you do, so i cant get the numbers you do. but i found that using a middle line of 4.4-4.6 (era: as long as one pitcher is above and one pitcher is below) so once i see that, i then look at of they have a difference of >.5 era. i then take the better pitcher and it seems to work pretty well. its not the only thing i use, but it gives me a good idea of who has a big pitching advantage. anyways, gl with everything curious. hope to see you around soon