The head coach and GM are insular and really don't like leaving their comfort zone. We've all seen this with their penchant for known quantities aka the Carolina player pipeline, and that school of though applies to coaches as well. Promote from within - it's the safe route, but sometimes you need to make a bold move.
"Draft, develop, and re-sign" sounds like a great strategy, it really does. But what happens if you draft too many mediocre players that don't develop?