42Jimmy GaroppoloSF201712-16437.0 Jimmy Garoppolo’s raw stats were impressive…Most raw passing yards in a five-game stretch for post-1970 NFL quarterbacks under age 30 (within first 16 career starts) 1Dan MarinoMIA19841-5899.9 1Andrew LuckIND20128-121,625 6Brett FavreGB199210-14405.1+107.0 Source: pro-Football-reference.com 4Kirk CousinsWAS20142-61,571 5Rex GrossmanCHI20061-5517.1+114.1 Jimmy reshaped the 49ers’ outlook in just five gamesBiggest gains in FiveThirtyEight’s Elo rating over a five-game stretch for QBs under age 30 who ranked among the top 50 in yards above backup over the same span of games 7Dan MarinoMIA19841-51,527 8Matt CasselNE20087-111,520 3Nick FolesPHI20139-13696.9 10Billy VolekTEN200412-161,473 4Russell WilsonSEA201212-16591.5+118.2 Still, it’s difficult to deny Garoppolo’s effect on the 49ers’ play down the stretch last season. Going into his first start (Week 13 against the Bears), San Francisco had a 1288 Elo rating — FiveThirtyEight’s preferred gauge of team strength at any given moment — which ranked second to last in the NFL. By the time Garoppolo had helped the Niners engineer their fifth straight win, San Francisco’s Elo had risen to 1452, good for a much more respectable 22nd in the league. That 164-point boost in team Elo was the most for any QB in the top 50 of our five-game leaderboard above, and it might be the best indication of how much potential Garoppolo brings to the table for his first season directing San Francisco’s offense. Includes playoffs.Source: Pro-Football-Reference.com Includes playoffs.*Yards above backup is a metric that credits a QB for his passing and rushing yards, with adjustments for touchdowns and interceptions, and the defensive quality of the teams he faced.Source: PRO-FOOTBALL-REFERENCE.COM … QuarterbackTeamYearGm. SpanYds Above BackupElo Gain 2Kurt WarnerSTL199911-15725.8 5Boomer EsiasonCIN198512-16639.3 …but he falls upon further adjustmentMost adjusted yards above backup* in a five-game stretch for post-merger NFL quarterbacks under age 30 (within first 16 career starts) 9Jon KitnaSEA19996-10411.5+104.8 3Cam NewtonCAR20111-51,610 QuarterbackTeamYearGM. spanYds above backup 9Richard ToddNYJ19773-7603.2 10Dak PrescottDAL20167-11602.7 7Tony EasonNE19844-8623.0 QuarterbackTeamYearGm. spanPass Yards 5Kurt WarnerSTL199911-151,563 9Daunte CulpepperMIN20007-111,499 2Marc BulgerSTL20034-81,624 No quarterback has ever earned more with less of a sample than Jimmy Garoppolo. After a midseason trade, Tom Brady’s latest former understudy had just five starts for the San Francisco 49ers1In his first appearance with the team, he went 2 for 2 with a touchdown in relief of C.J. Beathard. before becoming eligible for free agency. He won every one of those games for the previously moribund team and was handed $137.5 million for five years in return, which made him the highest paid QB in the NFL at the time. Again, this was for five starts of work in San Francisco — or 246 fewer games than Brady has started in New England.There’s really nothing else to go on. Garoppolo had played so sparingly before being traded to the 49ers that Bill Belichick and company were able to get only a second-round pick in return.There’s no debating that Garoppolo was very good in the scarlet and gold. The only question is how good. Is the weight of the sample such that fans should expect Garoppolo to earn his contract and propel the 49ers into a new era of excellence? Or is he overrated, piling up passing volume for a 1-10 team that was playing out the string on a lost season?According to classic barometers like passing yardage, Garoppolo’s five-game run to close last season does indeed rank among the most impressive rattled off by a young quarterback in NFL history. Going back to the 1970 NFL-AFL merger, we looked for similar five-game runs within a QB’s first 16 games as a team’s primary passer,2Meaning he led the team in passing attempts during the game but wasn’t necessarily the starter. filtering for QBs under age 30 — passers who generally fit Garoppolo’s profile as a fresh starter in the league. Only five quarterbacks — Andrew Luck, Marc Bulger, Cam Newton, Kirk Cousins and Kurt Warner — had a stretch of five consecutive games with more raw passing yards than Garoppolo did: 7Vince FerragamoLAR19803-7586.4+106.3 4Colin KaepernickSFO201215-19679.8 10Dan MarinoMIA19841-5899.9+93.6 3Ben RoethlisbergerPIT20044-8433.6+119.1 That the stretch represented Garoppolo’s entire body of work as his new team’s starter makes him look even more impressive — and that’s without considering his pair of exceptional games in 2016 as New England’s fill-in while Brady was suspended for his role in Deflategate.But there’s more to evaluating a quarterback than simple passing yards. If we take into account touchdowns, interceptions and rushing stats (plus adjust for strength of opponent) using our “yards above backup” metric, Garoppolo’s stretch-run performance takes a bit of a step back relative to history.Over those five games, Garoppolo had six touchdowns but also five interceptions, and he added nothing with his legs. He also faced a mixed bag of defenses that ranged from dominant (the Jaguars) to mediocre (the Bears) to downright bad (the Texans). And the Week 17 win against the division-winning Rams is less striking when you consider that L.A. sat many of its starters, including defensive player of the year Aaron Donald and standouts Alec Ogletree, Connor Barwin and Robert Quinn. After adjusting for all of that, Garoppolo’s five-game stretch still cracks the top 50 for young post-merger QBs, but it no longer seems quite as reliable a predictor of his future — particularly relative to the size of his contract. For every Dan Marino atop the ranking, there are some Tony Easons and Richard Todds as well. Not to mention the very glaring presence of a previous San Francisco QB much higher on the list: Colin Kaepernick. When adjusted for opponent strength, Kaepernick’s 2012 run from Week 16 to the Super Bowl was topped by only three quarterbacks in our sample. 6Jimmy GaroppoloSF201712-161,542 2Nick FolesPHI20139-13696.9+138.6 8Joe MontanaSF19812-6495.8+105.6 1Jimmy GaroppoloSF201712-16437.0+164.1 8Chad PenningtonNYJ200213-17612.7 6Daunte CulpepperMIN20004-8630.1 While the 49ers’ offensive boost, from 17 points per game with other starting quarterbacks to 28.8 with Garoppolo, can’t be fully explained by their QB’s statistics, there’s no doubt that much of this was earned from scrimmage. In its 11 games without him as the starter, San Francisco averaged 4.9 yards per play, 24th in the league. At 65.6 plays per game, that adds up to 322 yards. With Garoppolo, the Niners averaged 6.1 yards per play, which ranked fourth in offensive efficiency during games 12 through 16. And the play count also rose, to 67.2 plays on average, resulting in 410 yards per game.To quantify that boost of 88 yards per game, consider that NFL teams since 1990 have generated an average of 1 point for every 15.4 yards. So that equals 5.7 more expected points for the 49ers with Garoppolo at the controls (26.6 points per game) than without (20.9), not adjusting for that mixed bag of opponent quality.While about 6 points of added value may not sound like much, it’s what the oddsmakers subtract from a team when a top NFL quarterback is forced to miss a game. And we can definitely count Las Vegas among Garoppolo’s believers. This year, the sports books expect the 49ers to win 8.5 games with a full season of Garoppolo. That’s after they expected just five wins for the team before the start of last season, when Garoppolo was still stuck behind Brady.