Ted Karras has done a great job and definitely earned a long-term deal as a starter. We should lock him up quickly before he becomes a high-priced FA.
As for Deiter, well, this is a competitive industry. We drafted over him with Solomon Kindley and Robert Hunt who can both play guard. Our first option at center, Ted Karras, has proven very good. That means Michael Deiter is now competing for a roster spot more than anything. We have a lot of 2021 draft picks, and we should draft another couple OL prospects to compete all across the line, and that should include one guy who is a C/G combo guy to compete directly with Deiter and possibly be our back-up/replacement if we lose Ted Karras to FA. At this point, it's up to Deiter to prove the roster spot is his. If we lose Karras, I suspect we'll draft a starting C rather than give it to Deiter without a fight.
I like the kid, but this is a prove it industry. That goes for Mario Williams, Tua, and Michael Deiter alike. If you're good enough, you play. If you're not, you hit waivers and hope someone wants to roll the dice on you.