Kolb has been lights out this year. His ERA and WHIP are 0.98, and 0.83 respectively. He has saved 21 consecutive games -- the same amount he finished with last year.
What is interesting is his lack of strikeouts (8). His low walk totals (4) make up for this though, so there should be no concern over his strikeout totals. Kolb's stats show that he isn't a strikeout pitcher, which is fine as along as he gets outs.
If you can get a top level bat/arm for him, do it. Don't you dare sell him short though, or you'll regert it!