Game playing time does impact the learning curve for your players. Further more, the more minutes played, the more impact. This is why you will see your starters improve more quickly than your reserves, with the presumption that they get more PT.
Also, at one point, prior to the most recent engine change, playing against a particular offense or defense would improve your team's IQ. For instance, you face a ton of teams who play the triangle, your team may move from an F to a D- in that offense, even though you play the Flex. Not sure if this has been continued in the new engine or not.