Every NFL team has to navigate a delicate balancing act when building their offensive line. The easiest way to acquire talent is to use high draft picks and sign top free agents. But doing so again and again could well lead to a roster which is unbalanced and a salary cap situation which is untenable.
The other, more difficult, route is to find and coach up under-the-radar prospects with the traits to start. That could give you solid depth in the short term and a low-cost starter in the intermediate and long terms — as well as allow the team to use premium resources to address other positions.