As a podiatrist this is the most common problem we treat. Plantar fascittis is a ligament on the bottom of the foot that can become inflamed by normal or strenuous activities.  For the average person (non-athlete) it can be treated conservatively and easily by mainly stretching, physical therapy and possibly 1-2 injections. I also use a lot of topical medications with non steroidal medications able to penetrate into the arch and heel and into the plantar fascia. However for an athlete they require more stress on the arch especially with the type of shoe gear and cleats they have to wear. The type of turf will make a big difference too and weight of the player. Once you get PF it is very hard to get rid of without significant rest, change of shoegear or orthotics. I believe that Albert Pujols will have a hard time fully recovering from this issue since he has had this problem since his early days in STL.