Ryan Blaney left New Hampshire with more than just a win. The Team Penske driver became the first to lock himself into the Round of 8 with a victory at the Magic Mile, and he did it in the same way he’s built his playoff run: with sustained speed. William Byron, the regular-season champion, continues to match that standard. A unique metric shows why the two drivers have set themselves apart as NASCAR's most consistent performers in 2025.Thirty races into the Cup Series season, every driver has had flashes of brilliance, but few have paired them with race-long consistency. Measuring how many times a driver’s average lap time across a race ranked inside the top 10, Blaney and Byron both sit at the top with 19 out of 30 races. Daniel Cespedes posted the numbers on X:"Number of races with a Top-10 average lap time (through 30 races):"It means that in roughly 63% of the season so far, William Byron and Ryan Blaney delivered full-race pace good enough to contend. That’s a level of dependability that no other driver has matched.Christopher Bell, Kyle Larson, and Tyler Reddick follow close behind with 18 each, but the edge matters. Week after week, Blaney’s No. 12 Ford and Byron’s No. 24 Chevrolet have managed traffic, tire wear, and execution better than anyone else. It’s not about a single quick lap in qualifying or a strategy gamble, but the ability to keep running at the front no matter the track type or circumstance.Further proof lies in NASCAR’s Racing Insights ratings, which evaluate drivers across five categories: speed, long-run speed, passing, defense, and restarts. In this Round of 12 stretch, both Byron and Blaney are near the top of every column. Byron ranks second in speed, third in long-run speed, second in passing, fourth in defense, and first on restarts.Ryan Blaney sits alongside him with first in speed, long-run, and passing, while slotting sixth in defense and fourth on restarts. Taken together, they explain why Blaney and Byron have set the bar for the field heading into Kansas.NHMS dominance highlighted Ryan Blaney and William Byron’s edgeRyan Blaney (12) and William Byron (24) during the 2023 NASCAR Championship race. Source: GettyWilliam Byron’s path into the Round of 12 wasn’t spotless. He finished outside the top ten in the first three playoff races and stressed 'methodical progression,' a mindset he carried into Loudon. The No. 24 Hendrick Motorsports Chevrolet set the pace in practice at 127.834 mph and then backed it up in qualifying with a 29.373-second lap to earn P5. HMS has long struggled at New Hampshire, so Byron’s showing offered relief at the right time.Ryan Blaney, meanwhile, confirmed Ford’s weekend strength. While Byron topped the single-lap charts, Blaney’s No. 12 dominated long-run averages, topping the 10-, 15-, 20-, 25- and 30-lap metrics. That form carried into race day. Team Penske and their Wood Brothers ally led 273 out of the 301 laps, with Blaney leading 116 on his way to victory. Byron was the only Chevrolet to consistently challenge, bringing home a P3.(L-R) William Byron, Joey Logano, Ryan Blaney, and Tyler Reddick at Phoenix Raceway. Source: GettyThat result leaves Blaney on top of the playoff standings with 3084 points, just two clear of Byron at 3082. Both now hold big point cushions above the cutline with six races left. While the postseason picture remains wide open at this stage, one fact is hard to deny: Ryan Blaney and William Byron's consistency is elite.