Let's take Heredia, since I mentioned him in the thread. He's had some games since then so it will be interesting to see how he looks now.
-I found the league averages for my franchise. I was going to do AVG/OBP/SLG/ERA/FIP so that's what I calculated.
So for my carryover (where Heredia is playing), the average ERA is 3.27 (yeah, it's become a pitcher paradise). I put average FIP the same though I should have figured it since FIP scales to leagueRA, not ERA, but it's usually very close. Even in the real game, MLB FIP was 3.96 in 2015...and so was ERA.
-So then I find the number of innings he pitched and his weighted average performance. I use the most recent year and then, ideally, 1 year prior and then 2 years prior. If the player barely played, then I have to decide what to do. Maybe I ignore it and end up regressing more heavily (against his 1 or 2 years) or combine them (and treat it as one year), etc.
For weights, I weight current/most recent *5, Year-1 * 4, Year-2 * 3.
For Heredia, I would use these for him:
2022 (current year since midseason) - 79.1 IP, 2.50 ERA, 2.46 FIP
2021 (1 year prior) - 136.2 IP, 3.36 ERA, 3.20 FIP
2020 (2 years prior) - 154.2 IP, 3.32 ERA, 3.20 FIP
That gives a weighted average of:
117.3 IP, 2.99 ERA, 2.89 FIP
-Then I decide how much league average to include in the projection. I have a spot on my spreadsheet where I can just put in how many PA/IP I want to use. That gives me some judgement room. A guy like Harper or Davis I might just put in what he has (because these guys have established their levels), for a guy like Heredia with just 117 weighted innings, he gets more regression, but not a ton.
I have the innings set to 200 as a base (adjusted as needed - but 200 is fine for Heredia, imo).
-I also need age adjustment. The base is 29 (as in Marcel) and the age adjust is .0045 (also like Marcel). However, since I can see the player development, I will "fudge" the player's age to match his in-game trajectory. If it's usual for his age, I just use his age. If he's rising faster or declining slower than usual, I'll "make him younger", and if the opposite is true, I'll "make him older".
-So then I'd take what Heredia's done, "fill in" the rest with league average innings, apply the age adjustment I want and come up with the result. For Heredia, I used his straight physical age since his progression is not unusual.
projFIP = (((2.89 * 117.3) + ((200 - 117.3) * 3.27)) / 200 - ((29 - 27) * .0045)
(I subtract age adjustment for pitchers since lower is better and younger = positive age adjustment.)
That gives me a projection of 3.04 for his FIP. Against the 3.27 league average, that's a FIP- of 96.
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