We dont often disagree BR, but I think Sabathia will get in during the first 5 years. The big difference between these two is the Sabathia was the best pitcher in baseball for a few years, Pettitte really never was. They do have somewhat similar numbers career wise, but they got there different ways, AP was consistent, Sabathia had a great period and less good after. Sabathia's number overall are better, similar, but better. And really what is keeping Pettitte out is the Steroid stain, the lack of a dominant multi year period and really just good numbers over a long career.
In Baseball References Hall of Fame Monitor stat AP actually finishes higher, but nothing else really indicates that. He rarely lead the league in anything (wins once, games started 3 times) and had very few Cy Young votes in his career.