CFB ratings movers, week 8: Boston College climbs 19 spots, and LSU is number 3 after winning at Auburn

Boston College had the biggest single gain in week 8, and LSU is number 3 in our rating after winning 38 to 17 at Auburn. Boston College won 49 to 27 at Georgia Tech against an expected margin of minus 6.78 and gained 3.838 rating points, moving from 100th to 81st, while Georgia Tech lost 3.838 and fell from 80th to 95th. Ole Miss lost 34 to 27 at Texas when our rating expected an even game, about 0.02 for Ole Miss, and fell from 5th to 7th. Ohio State and Georgia were idle and stay 1st and 2nd. Cincinnati had the largest climb, 79th to 59th, and Iowa State the largest drop, 51st to 70th.

Every rating, rank, expected margin and move here is from our in-season CFB rating, the weekly update layer on top of each team’s preseason number. The week 8 rows were written after the week’s finals, and each team’s entering rating below equals its week 7 row, which we checked for all 138 teams. “Rank” always means rank in our rating across the 138 FBS teams we rate, not any poll. Figures are rounded from stored values. A rating and its move are each rounded to three decimals on their own, so a week 7 rating plus its move can miss the week 8 rating by 0.001.

How a move is computed

Each team’s rating moves by one number: a weight times its error. The error is the game’s margin, capped at 28, minus the margin our ratings expected. The expected margin is the team’s rating minus its opponent’s, plus 2.5 points for home field, minus 2.5 on the road, and nothing at a neutral site. The weight shrinks as the season goes on.

Worked example, Boston College on the road at Georgia Tech:

• Expected margin: Boston College’s entering rating of minus 6.486 minus Georgia Tech’s minus 2.202 is minus 4.284. Boston College was on the road, so subtract 2.5, for minus 6.784. Our rating had Georgia Tech winning by about 7.
• Actual margin: Boston College 49, Georgia Tech 27, so plus 22. That is under the cap of 28, so it counts in full.
• Error: 22 minus minus 6.784 is 28.784.
• Weight: a team’s seventh game, with six already played, carries a weight of 2/15, or 0.1333.
• Move: 28.784 times 2/15 is 3.838 rating points.

Georgia Tech, on the other side of the same game, was also playing its seventh game, so its weight was also 2/15. Its error was minus 28.784, and 28.784 times 2/15 is a loss of 3.838, the same size as Boston College’s gain.

That weight comes from setting the preseason prior to be worth about eight games of evidence. We walk through that choice in the preseason prior is worth eight games. Two consequences matter for this week. Each team’s weight depends on how many games it has already played: 69 teams in their seventh game carried 2/15, 42 in their eighth carried 2/16, and Eastern Michigan, in its ninth, carried 2/17. The other 26 teams were idle. And nothing past 28 points counts, even when the opponent was supposed to be much worse.

Why a loss can raise a rating

Utah State is the clean case. It lost 20 to 17 at Texas State, a margin of -3, and its rating went up 1.094. Our rating expected Texas State to win by about 11.2: Utah State’s entering minus 5.941 minus Texas State’s 2.764 is minus 8.705, and Utah State’s road game takes it to minus 11.205. The error is minus 3 minus minus 11.205, which is 8.205, and 2/15 of that is +1.094. Utah State moved from 98th to 87th, from a rating of minus 5.941 to minus 4.847. Texas State, with the same weight, lost the same 1.094 for the win and fell from 49th to 58th.

It was not the only one. Rice lost 51 to 49 at Florida Atlantic and gained 0.829, and Eastern Michigan lost 24 to 20 at Ohio and gained 0.806. Ohio’s home win cost it 0.857 and dropped it from 81st to 83rd. Across the week, 7 teams lost and still gained rating points, and 7 won and lost them. One of those 7 was Alabama: it beat Texas A&M 31 to 20 at home against an expected margin of 13.76, and lost 0.345. Texas A&M, on the other side, lost by 11 on the road against an expected minus 13.76 and gained 0.345. No team in a rated game played an FCS opponent this week, so the minus 22 we pin on FCS teams did not enter any move.

None of that is a verdict on the games. With Texas State expected by 11.2, a 3 point loss on the road beat the expectation by 8.2 points, and beating the expectation is what moves the number up.

Biggest risers

Margin and expected margin are from the team’s side. “Site” is home or road for the risers and fallers, taken from the game results.

Team	Our rank, wk 7 to wk 8	Rating change	Opponent	Site	Margin	Expected
Boston College	100 to 81	+3.838	Georgia Tech	Road	+22	-6.78
Cincinnati	79 to 59	+3.407	Texas Tech	Home	+13	-12.55
UL Monroe	137 to 134	+3.071	Troy	Road	+7	-16.03
UTSA	55 to 44	+2.874	Tulane	Road	+23	+0.01
Wyoming	128 to 113	+2.838	Air Force	Home	+14	-8.71
Hawai’i	126 to 112	+2.761	Northern Illinois	Road	+35 (counts as 28)	+5.91
Delaware	113 to 103	+2.747	Missouri State	Home	+23	+2.40
Illinois	61 to 47	+2.745	Oregon	Home	+11	-9.59

Cincinnati’s 37 to 24 home win over Texas Tech came when our rating expected Texas Tech by 12.55, a 25.55 point miss, and moved Cincinnati up 20 spots, the most of any team. UL Monroe won at Troy 21 to 14 against an expected margin of minus 16.03, and is still 134th of 138. Hawai’i’s 56 to 21 win at Northern Illinois was by 35, but the part past 28 did not count.

Biggest fallers

Every faller is the other side of a riser’s game.

Team	Our rank, wk 7 to wk 8	Rating change	Opponent	Site	Margin	Expected
Georgia Tech	80 to 95	-3.838	Boston College	Home	-22	+6.78
Texas Tech	14 to 28	-3.407	Cincinnati	Road	-13	+12.55
Troy	107 to 121	-3.071	UL Monroe	Home	-7	+16.03
Tulane	73 to 84	-3.066	UTSA	Home	-23	-0.01
Air Force	74 to 85	-3.027	Wyoming	Road	-14	+8.71
Northern Illinois	136 to 137	-2.945	Hawai’i	Home	-35 (counts as -28)	-5.91
Missouri State	112 to 126	-2.747	Delaware	Road	-23	-2.40
Oregon	16 to 26	-2.745	Illinois	Road	-11	+9.59

Each game pairs the two teams, but each side moves by its own weight, so the two moves match only when both teams have played the same number of games. Three of these eight pairs do not match. UTSA gained 2.874 at 2/16 while Tulane lost 3.066 at 2/15. Wyoming gained 2.838 at 2/16 while Air Force lost 3.027 at 2/15. Hawai’i gained 2.761 at 2/16 while Northern Illinois lost 2.945 at 2/15. In each case the heavier weight went to the team with fewer games played.

The top 10 after week 8

Ohio State is number 1 in our rating, at 23.896, and Georgia is second at 22.977. Both were idle in week 8, so neither rating moved. LSU is third at 22.317, up 2.014 from 20.303, and moved from 4th to 3rd. Alabama is fourth at 21.598, 0.719 behind LSU.

Rank	Team	Rating	Change from week 7	Rank last week
1	Ohio State	23.896	0.000	1
2	Georgia	22.977	0.000	2
3	LSU	22.317	+2.014	4
4	Alabama	21.598	-0.345	3
5	Miami	20.408	+1.082	6
6	Notre Dame	19.193	0.000	7
7	Ole Miss	18.872	-0.937	5
8	Texas	18.221	+0.937	9
9	Indiana	17.200	+0.298	10
10	Tennessee	16.484	-1.010	8

LSU’s 38 to 17 win at Auburn was by 21 against an expected margin of 4.89. The error was 16.11, and 2/16 of that is a gain of 2.014. Alabama’s 31 to 20 win over Texas A&M at home was by 11 against an expected 13.76, so the win cost it 0.345 and dropped it from 3rd to 4th as LSU passed it. Miami beat Pittsburgh 52 to 23 at home, a margin of 29 that counted as 28, against an expected 19.88, and gained 1.082, which moved it from 6th to 5th. Texas won 34 to 27 at home over Ole Miss, so Ole Miss lost 0.937 and fell from 5th to 7th, and Texas gained 0.937 and moved from 9th to 8th. Indiana won 13 to 6 at Michigan against an expected 4.62 and moved from 10th to 9th. Tennessee lost 27 to 24 at South Carolina when our rating expected Tennessee by 5.08, lost 1.010, and fell from 8th to 10th. In all, 26 teams were idle in week 8, and 3 of them were in the top 10: Ohio State, Georgia and Notre Dame, which moved from 7th to 6th without playing.

Next week

26 of the 138 teams moved 10 or more spots in our rating this week, and 1 moved 20 or more, Cincinnati at 20 spots. Last week’s edition flagged Ole Miss at Texas and LSU at Auburn as the two games between teams in our top 20. Texas won 34 to 27 and LSU won 38 to 17, and the moves from both games are above. The week 9 schedule has no game between two teams in our current top 20. The full board, in-season through week 8, is on our college football power ratings page.