That's the claim because he decided last year that Kromer is the root of the problems and won't back off that opinion. Some people just keep digging once they get in a hole. I'm blown away that O'Connell has fixed our problems despite the fact that he has no experience coaching OLs, no experience scheming running games, and isn't the person who is primarily responsible for what we do on offense (that's Sean McVay).
What has fixed our OL is a combination of improvement from young OLs, more experience and chemistry from guys who gelled down the stretch last year, better scheming from McVay, and our two OTs not playing through injuries (or in Havenstein's case, missing most of the season). It's plain as day to anybody who is willing to look at things remotely objectively. But if you admit those things, you can't deny Kromer some credit in the OL's improvements. He's a top 5 OL Coach in the NFL, and we're quite lucky to have him. I remember the Loney and Boudreau coached OLs. Thank god for Kromer.