A recent study found that, unlike other snakes, strike performance in BPs declines rapidly over their first 18 months. The author's best guess is that captive BPs are just too fat and happy to give a damn. It's a small study, 10 BPs over 3 years, and it doesn't explain why this is unique to BPs. But if you've noticed your BPs performance waning, at least you know that it's not just your BP.
If you want more, Lori Torrini discusses the study in further detail here. She says the article is open access, but all I was able to find without paying was the abstract. If you find it, please add it to the thread. Thanks.