Your argument is reductionist.
If we are looking at it from an evaluative standpoint, then yes, Clemson was 4-4, and its postseason hopes were determined by the record. In that sense, Clemson “was” what its record said it was.
But in this discussion, we are not talking about what Clemson was as far as its postseason hopes were concerned, but what it was capable of, and what it had shown it was capable of when it played us. Your argument is reductionist because it simplifies the assessment of a football team's talent and performance solely based on its win-loss record, neglecting the multitude of factors and specific plays that contribute to the team's overall dynamics and potential for success. We were playing a team that had made many mistakes and therefore was 4-4, but we were also playing a team that had a top 10 defense, which is top-five now, and had shown that it was very difficult for any team to defeat.
As mentioned, there is not a single team that was able to out play Clemson to the point where one could conclude that that other team was completely better than it was. If you change around a few plays here, and there than that Clemson team is now 9-2 or 10-1. Compare Clemson to a team like Boston College – you cannot take just a few plays here and there and say Boston College could have been 10-1 as it was soundly outplayed at a fundamental level by multiple teams. Was BC at 5-3 and 6-3 the same and/or as Clemson at 4-4? No, it wasn’t.
This is why the odds makers made the opening line what it was when Notre Dame and Clemson played — they knew how good Clemson was from a talent standpoint, help with a few plays here, and there, that it would have a near perfect record, and what it was capable of especially at home. If the oddsmaker thought that Clemson was some run-of-the-mill average team, they would not have made the opening line what it was.