​The Washington Commanders opened the preseason with a dominant 20-7 win over the Miami Dolphins on Friday night at Northwest Stadium. The win capped a successful week for Washington, which shared the field with the Dolphins on Wednesday in a joint practice.With most of the Commanders’ starters participating in the joint practice, head coach Dan Quinn gave most of them the night off for Friday’s preseason opener. No Jayden Daniels. No Terry McLaurin, Stefon Diggs, Chig Okonkwo, Bill Croskey-Merritt, Odafe Oweh, K’Lavon Chaisson, Mike Sainristil and several others.Marcus Mariota got the start under center for Washington, but departed after only a few plays with an apparent leg injury. Sam Hartman and rookie Athan Kaliakmanis went the distance for the Commanders. Friday’s win came down to Washington’s rookie running backs and a dominant defensive effort. Here are six standouts from the Commanders’ preseason-opening win. QB Athan KaliakmanisIf you just look at the numbers, not much separates Kaliakmanis and Hartman. However, Washington’s offense looked different with the rookie. His first two passes were completions. One was an impressive strike to Colson Yankoff. Compared to Hartman, the ball just jumped off Kaliakmanis’ hands. We aren’t sure if the Commanders will keep two or three quarterbacks on the 53-man roster. If they keep three, Kaliakmanis has already won the job. Hartman struggled early but settled down and looked much better than he did a year ago. But Kaliakmanis had the better overall night.RB Robert Henry Jr. We’ve been quietly hearing about Henry since the spring. While the focus was on Croskey-Merritt, Rachaad White, fellow rookie Kaytron Allen and Jeremy McNichols, Henry has been showing off in practice. The undrafted rookie from UTSA can fly. He’s also got some impressive wiggle. On his touchdown run, Henry showed a little bit of everything: vision, patience, and explosiveness. Henry also had an impressive pickup in pass protection. If he can string together two more performances like this, he’ll be hard to keep off the 53. RB Kaytron AllenHenry had more flashy runs, while Allen had the big, sturdy runs you’d expect from him. He carried the ball 23 times for 85 yards and a touchdown. There was already talk that he’d be Washington’s short-yardage back in 2026, and he did nothing to dispel that notion. Allen is a different type of back from everyone else on the roster. That’s a positive. Offensive coordinator David Blough can use him in goal-line situations or late in games when they’re trying to protect a lead. WR Jaden BradleyTwo players we’ve heard a lot about since OTAs and the beginning of camp are tight end Colson Yankoff and undrafted rookie wide receiver Jaden Bradley. Yankoff is making the roster again. He put together another good night. So did Bradley. Bradley flashed off a little bit of everything, almost blocked at least two punts, caught two passes and had a couple of impressive block