You've got to weigh the risk of the pick against the potential value and factor in the price. McPherson as a 5th round pick is not that expensive. He has issues in his past, but hasn't done anything wrong in a while (low risk). His value on the other hand can be huge. I think he's well worth it.

Lyman is similar, but much more risky. He was only a 4th round pick - not terribly expensive. However, he had injury problems his entire college career - that's high risk. His potential value is hard to ascertain. Would ha have been anything more than a backup? As injury prone as he is it seems unlikely that he could have, but who knows?