This is the fifth in my series on possible extensions for the Braves' young core players. Here are the links to part one (on Martin Prado, alas), part two (Jason Heyward), part three (Freddie Freeman), and part four (Kris Medlen). In the last post, by the way, 73% of TC readers favored extending Medlen at the cost I proposed ($27M over 4 years). In 2012, Craig Kimbrel posted one of the most mind-bogglingly great relief seasons in history. Few would doubt that he is now the most dominant closer in baseball. Add in the fact that he's only 24 (he turns 25 in May) and has yet to enter arbitration, and Kimbrel is one of the Braves' most valuable players. Normally, when you have a young player who dominates his position, you'd be eager to lock him up to a long-term extension. However, Kimbrel's position--relief pitcher--adds a huge amount of uncertainty to future projections, which makes such extensions very dicey. I talked in the last post about how all pitchers are risky long-term, but that goes double (or triple) for relievers, who are infamous for their volatility even in absence of injury. As we'll see below, performance declines among top young relievers are more the rule than the exception.