Granted he was a fine officer of great potential, but if we accept the timeline put forth in "Pegasus," in the sixth production season Riker's commissioned career was only into it's twelfth year! That means when he was offered the Aries, he was only seven years a commissioned officer--not plausible when you consider it in that frame of reference.
Pretty quick ascension up the ranks there, and wasnt there more than one episode where characters said that most officers desired to sit in the chair. I think even Eddington said as much before he realised his place was with security, for that time I guess Riker found his place to be as the XO to the best Captain in the fleet serving on the best ship with the best crew.
If he was eligible to make Captain in only 7 years I wonder how often this happens, or is it only rare examples such as Picard and Kirk in whichever reality for whatever reason who make Captain young.
Maybe Pikes "You could be an officer in four years. You could have your own ship in eight." in ST09 is more than just recruitment spiel?