When the Buffalo Bills host the Houston Texans on Sunday at Highmark Stadium in Orchard Park, N.Y., the game should provide a study of contrasts at the most important position on the field.For the Bills (2-1), fourth-year quarterback Josh Allen is coming off a sensational performance against Washington, one in which he completed 32 of 43 attempts for 358 yards and four touchdowns in a 43-21 victory. Allen did not suffer a turnover or a sack. The effort, which earned Allen AFC Offensive Player of the Week honors for the seventh time, was emblematic of both his immense talent and the strides he’s made since a ragged rookie season.”I like how Josh took what the defense was giving him at times and other times he created on his own,” Bills coach Sean McDermott said. “I think there was a good balance. I thought (Bills offensive coordinator Brian) Daboll did a good job of changing the looks to the defense and got him in a good rhythm, and then spreading the ball around to different targets is a healthy approach, as well.”Allen, the seventh overall pick in the 2018 draft, started 11 games as a rookie and completed just 52.8% of his attempts while recording more interceptions (12) than touchdown passes (10). He suffered 28 sacks and, like most rookies, often appeared lost against opposing defenses.After earning Pro Bowl honors last season, Allen appears to have unlocked his vast potential. He has thrown seven touchdowns against only one interception and is ascending the ranks as one of the premier signal callers in the NFL. While his development has been astonishing, it underscores the belief those closest to Allen had in him from the beginning.”You knew developmentally that he (Allen) was going to become what he has become right now, just with time,” said Texans coach David Culley, the Bills’ quarterbacks coach in Allen’s rookie year of 2018. “There were some fundamental things that he needed to correct, and obviously he’s corrected those right now. He’s playing at a very high level right now.”The Texans (1-2) are attempting to inch rookie quarterback Davis Mills along that same path of development. Mills made his first career start in the stead of veteran Tyrod Taylor (hamstring) last Thursday against the Carolina Panthers and, predictably, delivered an uneven showing.With Taylor unavailable against the Bills, the onus falls on Houston’s offensive staff to get Mills up to speed, or at least nudge him toward a performance superior to what he managed previously. Culley has a clear view of how Allen got to where he is and how Mills might follow.