Rich Cimini does a good job laying out reasons the San Francisco 49ers might consider trading for New York Jets cornerback Darrelle Revis.I'll give you five reasons to think twice.Philosophy test: Smart NFL teams know drafting well beats signing veterans from other teams to inflated deals. Drafted labor is cheaper, healthier labor. After spending big in free agency to prop up a shaky roster five-plus years ago, the 49ers have taken a disciplined approach to improving the team.