I never followed the Maryland circuit, but as far as I am concerned there have been suspicious move up trainers for as long as I have been around the game (since the middle 70s). As far as I can recall they were mostly limited to the claiming ranks. It wasn't until the period when Oscar moved up "Shifty Sheik" that it spilled over into the higher ranks of racing. If my memory is correct, that was an exception. That kind of stuff seems much more widespread now.

There have also always been trainers that managed to get high quality stock and whose success at developing it and spotting it managed to attract even more good stock. That invariably translated into an extraordinary winning record and horses that tended to outperform their figures as they developed. I've been betting lightly raced, well bred, high quality stock from the best barns since I read the Handicapper's Handbook by Tom Ainslie back in the "dark ages". Horses like that often have more in the tank than their speed figures suggest and trainers like that often move horses like that up when they get them and have a chance to work with them for awhile.