Since Top Rated Jumps has a 90% ROI, I may subscribe and start betting against his tips

just kidding, but indeed as you said it's impossible to sustain such result. By the way, are we on the same page, ROI or ROC (Return on Capital). 90% of ROC would mean current bankroll at 1900 starting from 1000 in just 85 picks, but I cannot see how a 90% ROI is possible, unless he released one or two winners at odds of 100 or 200?
Anyway, very encouraging indeed.