>>35028937First, look at pokemon with similarly "balanced" stats.
Arceus is used primarily as a support pokemon because of its ridiculous speed, titanic bulk, stellar movepool, and relatively mediocre attack. It sees play offensivly because of its access to great set-up moves and attacks to abuse them.
Mew is used primarily as a support pokemon because of its good speed and bulk, absolutely bonkers movepool, and mediocre attack.
Celibi is used primarily as a defensive support because of its good speed, decent bulk, good movepool, and typing.
Manaphy is typically used as a set-up sweeper because of its good speed, amazing set-up move in Tail Glow, good bulk, and workable movepool.
Jirachi is a cheesy motherfucker because of its good speed, and Serene Grace boosted paraflinch.
Now look at Silvally.
It has good speed and bulk, low attack, and a movepool full of offensive moves with holes in its coverage, almost no support moves, and parting shot.
It tends to be used as a Z-Parting shot stooge, that can explode afterwards. Oh, and now as a defogger, so now it can't even just fucking die when its healed someone more important.
It has only Swords Dance (And Flame Charge) to set up with, even though it doesn't have the movepool to take advantage of it.
It has Arceus' handicap of having either an item or an ability, but has it even worse since it doesn't get the extra STAB bonus, or Z-Move and its ability at the same time.
Balanced stats are inherently defensive, and a defensive pokemon needs a wide movepool. Silvally lacks the stats to be an offensive threat on its own, and lacks the toolbox to make its mediocre offensive presence known.
Silvally just can't even.
