Kicker
Every player has to perform a Primary role in a team, be it defending, striking, tackling etc....that is his or her strength.
But for the team to be effective the qualities that the player does not bring to the table must be covered or done by the teammates.
Now if a person is deficient in a particular area, more work will have to be done by the teammates in order for balance to be restored.
Its another way of saying...given his supporting cast, how would they cover the things he doe do good.
e.g. With Latapy in the midfield you have little defensive cover coming out of him...yes he may pelt a tackle and track back, but you not expecting that out of him. So who do you have in the middle to balance it out...Birchall Primary, Yorke Secondary and then WHitley.
Now if a mans weakness is glaring....then his teammates have more wuk to do, or their role is changed....e.g Whitley is a runnning, beating attacking Phenom for Jabloteh, but in TT colours he have to humble heself and play defensive mid or not as attacking because the Boss Latapy run things.
Now going back to the Glenn/Donovan issue....If you look at each players deficiencies...and how it will impact on work being done by the teammates
around them a sensible coach would go for the option that results in less load or work per supporting player. Thus the supporting players can concentrate on their primary role.
Lets give another example...Stern.
He will not run for no ball and you do not expect him to take any ball and run at a defence. He is a trap and screen man and goal poacher...........He is totally deficient at being a counter attack man or penetrative player.
Thus to hide his lack of speed you change the formation to suit Sterns strengths or you place players around him with the attributes he does not have. Hence Scotland, Cornell, Kenwyne etc if playing a 4-4-2 are his striking partners.
Cornell nor Donovan are "stars" to dictate how we play around them....thus they would both be players who have to get with the system.
The logic of my thought process follows that Donovan is more of a complete player hence lessening the workload on his teammates allowing them to perform their roles more effectively.