There is a decent likelihood that if he only stocked 15 5" crappies, they were all eaten before they could pull off a spawn this spring. Particularly if there are a large number of 15" plus bass in the pond. However, it only takes two to tango... If a male and female crappie did survive and managed to find each other, you can almost guarantee they spawned. How the crappies will affect the pond will be interesting. I sometimes feel that stocking crappies after the largemouth bass population has been given a chance to establish and get 20% of the bass population into the 15"+ is one way you MAY be able to get around some of the issues that crappies can cause in ponds. However, I still think it is risky and your buddy should closely monitor his pond for signs of the crappie spawning. If they did, he needs to vigorously fish for them and remove ANY and ALL crappies he catches.