My opinion on the difference between Offensive Tackle and Guard has changed over the last 10 years.
In the past, Offensive Tackle were bigger and stronger than Guards due to the fact that the power running game still dominated college football. Offensive Guards were quicker and more agile so they were capable of pulling, trap blocking and getting to the 2nd level (LBs). This was also an evolution that was reinforced by many schools using the 3-4 defense. A defense which Guards were uncovered and DE were primarily stronger-built, run defenders.
Today, many schools implement the 4-3 pro-style defense with two massive run stuffing DTs and two lightning fast DE to pass rush off the edge. I think this is forcing offenses to adjust by looking for quicker more agile Tackles and stronger more physical Guards.
CW, being a very smart man, may be looking to recruit more Guard types and convert them to Tackles. In recruiting, we have went after some top-flight Offensive Tackles, but we seem to "go after" Guards with a lot more intensity than Tackles.