1. Very bad on the move. Dodging granades, mortars, artillery means actually not fighting/shooting - good players will use it against grens in many ways. Any sort of moving combat and they are completely useless (you can make them "dance" with tanks for example - they stop shooting completely - if you're lucky they won't even fire a shreck/panzerfaust as they can't "find" the position; another example would be running around them with any infantry unit - sometimes it looks as if you were circlestrafing an anti tank gun - often an undecided lmg operator won't fire at all before the opponent stops).
2. Effective long range only. Generally damage output long range is low - even when some unit is relatively good at it - that means it takes forever to inflict damage and it is much better to be effective medium short range. By being fought long range players don't have to be so focused as you have more time to react and retreat the unit that is being shot at. Close range you may lose the whole squad very quickly because you were doing something on the other side of the map.
3. A stationary unit is extremely vulnerable to all sorts of mortars, grenades and artillery. The unit is also very much "predictable" on the map as it has to seek for cover (which again makes it even more susceptible to mortars). Units on the move usually dodge mortars unless you predict where they will be in a moment and attack ground. Of course they are vulnerable when they stop - but this would be the players mistake when he/she knows there is a mortar around. Grenadiers "fighting style" is perfect for mortars operators.
4. Because it's a range unit tactically it will lose in many "soft" ways - for example a capping rifle squad will usually manage to decap the point being under fire (and retreat to heal before losing models) as grens must shoot from further away, that is from outside the capping circle - it could be a game winning factor in tight battles.
5. Another "soft" tactical inferiority of grens is that they are usually unable to finish off a retreating squad - even when it's retreating "through" groups of them. Very often they won't even be able to pick off any models on a relatively weak unit (sappers, rear echolon - which very often means they will be able to finish what they were doing and retreat only then).
7. Because they are four men squads they are much more vulnerable to wipes. Additionally, they are very bad at picking abandoned weapons - very often either you recrew the weapon and loose the squad or leave the weapon abandoned (I don't understand why you can't pick weapons with 2 people for four men squads - especially if there are 3 models on the squad left). Also after picking the weapon they must retreat immediately as one man that is left is completely useless. Picking weapons under fire impossible or you lose the squad - other infantry can do that to finish off a tank, for example.
8. Connected with the above - you must retreat them more often because when they've lost one or two models. Then they become very fragile and their damage is reduced. Because of that their battlefield presence is shorter in comparison to other squad.
This is the longest post in my life
