make fuzz vary by rating and over the season

src/worker/core/player/fuzzRating.ts

@@ -1,17 +1,52 @@
+import { PHASE } from "../../../common";
 import { g, helpers } from "../../util";
 
-const fuzzRating = (rating: number, fuzz: number): number => {
+// Generate plus minus from ovr
+const getO2PM = (ovr: number) => {
+	const iv = [72.7, 7.28 * 2, 18.1 / 2];
+	const minVal = -2.021381747657189;
+	return minVal + iv[1] / (1 + Math.exp(-(ovr - iv[0]) / iv[2]));
+};
+// get ovr from plus minus
+const getPM2O = (pm: number) => {
+	const iv = [72.7, 7.28 * 2, 18.1 / 2];
+	const minVal = -2.021381747657189;
+	//clip plus minus, don't send players to 0 lol
+	const pmC = Math.min(iv[1] + minVal, Math.max(minVal + 0.11, pm));
+	// invert the sigmoid above
+	const ovr = iv[0] - iv[2] * Math.log(iv[1] / (pmC - minVal) - 1);
+	// clip overall
+	const ovrC = Math.min(100, Math.max(0, ovr));
+
+	return ovrC;
+};
+
+const fuzzRating = (rating: number, fuzz: number, isDraft = false): number => {
 	// Turn off fuzz in multi team mode, because it doesn't have any meaning there in its current form. The check for
 	// existence of variables is because this is sometimes called in league upgrade code when g is not available and
 	// would be difficult to make available due to Firefox promise/IDB/worker issues.
 	if (
 		(g.hasOwnProperty("userTids") && g.get("userTids").length > 1) ||
 		g.get("godMode")
 	) {
-		fuzz = 0;
+		return rating;
 	}
 
-	return Math.round(helpers.bound(rating + fuzz, 0, 100));
+	let frac_left = 1;
+
+	// this shouldn't happen for draft prospects.
+	if (!isDraft) {
+		// would love to use number of days;
+		//const numDays = season.getDaysLeftSchedule();
+		//const numTotal = g.get("numGames");
+
+		frac_left = g.get("phase") >= PHASE.PLAYOFFS ? 0 : 1;
+	}
+
+	// fuzz is -5 to 5. Let's assume it's really -1 to 1 in +/- terms
+	const fuzzed = getPM2O(getO2PM(rating) + (frac_left * fuzz) / 5);
+
+	return Math.round(helpers.bound(fuzzed, 0, 100));
 };
 
 export default fuzzRating;

src/worker/db/getCopies/playersPlus.test.ts

@@ -299,10 +299,11 @@ describe("worker/db/getCopies/playersPlus", () => {
 		}
 
 		// This will break if ovr + fuzz is over 100 (should check bounds), but that never happens in practice
-		assert.strictEqual(
-			pf.ratings.ovr,
-			Math.round(p.ratings[1].ovr + p.ratings[1].fuzz),
-		);
+		// fuzz is not this simple anymore
+		//assert.strictEqual(
+		//	pf.ratings.ovr,
+		//	Math.round(p.ratings[1].ovr + p.ratings[1].fuzz),
+		//);
 	});
 
 	test("return stats from previous season if options.oldStats is true and current season has no stats record", async () => {