I was in one campaign where if you took one Veteran MechWarrior, you also had to take one Green, but the rest were Regular. Same went for vehicle crews, where one vehicle could have a Veteran crew, but then one had to be Green. Any further recruits came in as Green. You learned that you had to quickly train up at least one Green MechWarrior by running them in almost every battle, otherwise you risked not having enough Regulars to cover for injuries or losses. Running the Veteran and some Regulars in every battle, and leaving the greenies home, would be a short-term strategy doomed to failure in the long run.
As said, what you can do in the MechWarrior series games is nothing like tabletop play, and there's no way to compare the skills involved. The hit ratios on the tabletop only make sense in scattered cover, where the target only appears momentarily between obstacles. In an open field with an unbroken line of sight to target, the hit rates should be nearly 100% at the ranges in the game, even with current technology. Computerized tracking should easily adjust for changes in speed and direction, since anything with that much mass cannot change its movement vector all that quickly with the amount of traction available on most terrain. Picture 50 tons of Battlemech moving at 45 miles per hour tearing a deep rut in the ground as its foot slides out from under it during a rapid turn....