What in the world are you talking about? If you don't want to look at the statcast #s which is kinda wild, let's look at the traditional numbers
Irvin : 2.87era / 1.181 whip / 3.63 fip / 8.9 h9 / 0.9 hr9 / 6.2 k9
GRod: 3.27era / 1.232 whip / 3.31 fip / 8.0 h9 / 0.9 hr9 / 10.2 k9
Even without the dominant #s you can see that GRod has done better. His era & whip are slightly higher, the fip is better, he gives up less hits and strikes out more. And he's also covered more innings.
I like Irvin as well, but to say he's been better by 'quite a bit' is just flat our incorrect. All his #s suggest he's been a bit lucky and will likely regress as the season continues.
GRod likely 5 & dive? WHAT?!?!? Grod has pitched 6ip more than Irvin has on the season.