It's true that every game matters in the College Football Playoff, but you don't know which ones will matter the most until it's too late.

So here's your rearview mirror perspective.

Had the ball bounced a different way in just a handful of games, it could have changed the semifinal picture we have today. Penn State or Michigan could have been in. Ohio State could have been out. Oklahoma might have been in. Clemson could have been out.

Here's a look at the games that had the biggest impact on the selection committee's final top four, and what could have been:

Ohio State's September win over Oklahoma helped the Buckeyes compensate for not winning the Big Ten championship. Kevin Jairaj/USA TODAY Sports

1. Ohio State 45, Oklahoma 24 (Sept. 17): Proof that strength of schedule still matters. "I'm not sure Ohio State would have been in the [playoff] this year," CFP executive director Bill Hancock said, "if it hadn't gone and played Oklahoma." The Buckeyes wound up beating the Big 12 champion on the road, which helped them compensate for a lack of a division or league title. The Sooners finished No. 7 in the CFP's final ranking, giving OSU three wins against top-10 teams, along with Michigan and Wisconsin. On the flip side, imagine if OU had won this game. Even with the season-opening loss to Houston, the Sooners would have been undefeated in Big 12 play with a win over the Buckeyes, finishing at 11-1. Would that have been enough to give them the edge over Washington for the No. 4 spot? It certainly would have created a bigger debate.

2. Ohio State 30, Michigan 27 in 2 OT (Nov. 26): What if The Spot had been short of the first down on fourth-and-1 from the 16? What if Curtis Samuel never had the chance for that ensuing 15-yard touchdown run? If Michigan would have won The Game, it would have won the East and would have played Wisconsin -- a team it already defeated -- for the Big Ten title. Michigan was literally inches away from an entirely different ending to its story. No wonder Jim Harbaugh was "bitterly disappointed."

3. Michigan 49, Penn State 10 (Sept. 24): This was the dagger in PSU's résumé. Selection committee chair Kirby Hocutt said the Nittany Lions were "non-competitive." But if PSU had been healthy defensively, if it had won this game or even shown a pulse, would the committee have put it in the top four instead of Washington? If the Nittany Lions' only loss had been to Pitt -- which finished No. 23 in the final rankings -- and they had wins over Ohio State and Michigan, it's hard to fathom the Big Ten champs being out of the final top four.

4. Navy 46, Houston 40 (Oct. 8): This loss was devastating to Houston on so many levels. The Cougars beat Oklahoma in the opener in what looked at the time was a program-changing win. A top-four finish seemed possible -- until the loss in Annapolis. As the Group of 5's best chance at the playoff, Houston knew it needed an undefeated season to be taken seriously in the playoff conversation. It was never able to get back on track, losing two weeks later at SMU. Houston's decline also impacted Louisville's résumé down the stretch.

5. Clemson 42, Louisville 36 (Oct. 1): Louisville was stopped one yard short on fourth down -- a yard! -- with 33 seconds left in the game, and Clemson escaped as the top playoff contender in the ACC. In spite of the loss, though, there were some who argued Louisville was still a top-four team (at least until it lost to Houston). If Louisville had won this game, though, and had wins over both FSU and Clemson, it would have been undefeated heading into Houston and could have impacted how the Cardinals finished the season. Louisville would have been playing for the ACC title, and a whole lot more.

6. Colorado 27, Utah 22 (Nov. 26): If Utah would have won this game, three-loss USC would have won the Pac-12 South. Then what? Washington would have had a second chance to beat the only team it lost to during the regular season, and the committee probably would have had Washington in with a win over USC, too. What if USC would have won, though? The Pac-12 probably would have been left out entirely.

7. Central Michigan 30, Oklahoma State 27 (Sept. 10): In what was arguably the most controversial finish of the season, the officials incorrectly extended the game for one final play when it should have been over, allowing CMU to score on a Hail Mary and lateral (huh?!). The Cowboys and Mike Gundy were stunned and their disbelief lasted all season long. Had the officiating gaffe not happened, Oklahoma State would have been 3-0 heading into its next game against Baylor, a game in which it lost. The 2-2 start before October changed the entire season for the Cowboys and despite Gundy's protests, it was a record that couldn't be changed in the eyes of the committee.

8. Washington 45, Washington State 17 (Nov. 25): This game weighed heavily on the Pac-12's playoff hopes. If Washington would have lost the Apple Cup, Washington State would have won the North, and there's no way the committee would have put the three-loss Cougars in the playoff. The Pac-12 would have then had to hope that two-loss Colorado won the league, and even then wouldn't have any guarantee. Instead, it helped boost Washington's playoff résumé and catapulted the Huskies back into the committee's top four after sitting at No. 5 the previous week.