Those numbers are over 67 PA. Career numbers are better.
For his career, they do climb slightly, but bear in mind in the NL, the first two trips through the lineup mean he got to face pitchers for approximately 10% of his hitters. And even then, the SLG jumps up about .070 and he allowed 75% as many home runs to hitters third time through in roughly 50% of the plate appearances.
The reduced workload and reduced exposure helping him is really not a surprise. Bu the problem with this strategy is if the Sox try to limit their SP to 5IP every game, they will need 4 IP from their bullpen. And that is getting dangerously close to a 750-700 IP split between the to roles that I don't think the Sox relievers are very ready for...