You are partially right about Leary. Leary never played C. Jonesboys need a OG that can also play C. That was why Jonathan Cooper was signed in 2016 and did well both years as Jonesboy.
Leary was a tackle in college that had the same knee problem Mack had at UCLA. Leary converted to OG signed as a UDFA. Leary never played C. You want one of your starting OG to have experience at C or be able to move to RT. See John Fitzgerald, Tom Rafferty, Mark Stepnoski, Ray Donaldson, John Gesek, and Crawford Ker. All played OG and C. This keeps your line from going to crap when you loose a C or an OG. If your C goes down the starting OG can move to C, and you plug in a G which usually is one of your back up T.
Larry Allen type is what you want at pure G which is a former OT converted to G. See also Nate Newton, Kevin Gogan, and Herb Scott all converted T to G. At the Tackle position you want to get a pure LT which are hard to find/high premium draft pick or a LT that can play RT or a RT that can play LT. See Smith RT converted to LT, Collins LT converted to RT/OG, and Jim Cooper pure T. Rayfield Wright played basketball and TE before HOF LT for the Cowboys. The Dallas Cowboys were so good at converting 4-3 DT to LT/RT see Mark Tuieni, Pat Donovan, and John Fitzgerald was a DT converted to C (rare).
Unless Leary could play T in the NFL, he was one dimensional as a OG with no ability to swing to C. Jonesoys should have kept Cooper. You lose your C and do not have a strong back up that can play OG you are what you are now.
