Lennon has been in the team while Morris has been playing in the reserves because he was dropped. Newman is retiring at the end of the year so won't be a factor from next year, and currently is contributing. And like others have stated, Grigg, is having a good year and is valuable to the team, and deserves his spot in the 22.
And again, since his return Lennon has been subbed off once at three quarter time, and been the starting sub once, where sure he was left on the bench until half way through the last quarter, but in a game where the plan seemed to be to sub Edwards off in his retrun from injury, while also trying to maximise his game time to have him in good condition for finals.
This seems pretty reasonable for a guy who has had question marks over his endurance. He also plays in a position/role that Hardwick and the coaches tend to prefer to use as the sub, the medium forward/half forward, as we have seen Lloyd as the starting sub multiple times during Lennons return, as well as Gordon.