By Justin Barrasso As it has been for the last 600-plus days, the difficulty remains finding the right challenger for the dominant champion. A few takeaways were abundantly clear from Sunday night’s WrestleMania Backlash pay-per-view, most prominently the line of challengers for Roman Reigns’s spot as WWE and universal champion. While WWE has a surplus of frustrating qualities (like the callous way it cuts talent under contract), there is also no denying its roster is outrageously talented. That was on display at Backlash, where the majority of matches exceeded expectations. This was a night w…