The NTEP tests are done in relatively small plots with no shade, no traffic, and most of the data is collected during the first few years, some locations not even completing the whole 5 years of the test. They are usually more aggressive and already genetically heterogeneous. In that theory, seeded varieties should be stronger in preventing appearance of off-types, because they are already heterogeneous. Such a hope may be unfounded, however, because the running growth of bermudagrass forms circular clones, which allows more aggressive ecotypes to become dominant and distinctive. There is competition to prove that one variety is best, or at least generate a purchase decision.
Superintendents have a very difficult choice to separate fact from hype.
Part of the problem is that no one can tell how a grass will perform in the long haul. Although there are clearly differences among newer varieties, and one might even say that one is better than another under certain circumstances, the biggest factor cannot be measured. It is risk. As in other areas of life, golf courses vary in their acceptable risk-reward equation. All these people stand to win or lose based on choice of a grass variety.