It doesn't always work out this way but football can be a game of momentum.
Early Clemson looked like they might coast, at least offensively, but OSU made enough plays to match scores then Clemson's DB had to sit in the 1st half and then they lost their star LB and it was all downhill. Clemson's offense bogged down and OSU started flying around.
This lead almost looks to great based on the way these teams were playing going into the half but Trevor Lawrence is too good and he has too many weapons to think be won't at least get to 35.