Except that spell selection isn't all the shadowcaster has.
What's the tricksy wizard's hide check? Move silently check? Spot check? What bonuses is he getting from his armor? His buckler? Do his spells have material components? Somatic components? Verbal components? Are his hit points as high? How's his fort save? Not to mention that shadow magic mysteries tend to be on a 1 for 1 level superior to comparable spells (dancing shadows grants actual concealment, not fake concealment like displacement, killing shadows is d8 instead of d6, etc). Or that the shadowcaster is largely emancipated from issues like casting defensively, or having his spells countered or dispelled, and gets a permanent, better form of the darkvision spell.
You can't just consider offense. Defense is a factor. If all we considered was offense, of course the glass cannon classes would always win.
What's the tricksy wizard's hide check? Move silently check? Spot check? What bonuses is he getting from his armor? His buckler? Do his spells have material components? Somatic components? Verbal components? Are his hit points as high? How's his fort save? Not to mention that shadow magic mysteries tend to be on a 1 for 1 level superior to comparable spells (dancing shadows grants actual concealment, not fake concealment like displacement, killing shadows is d8 instead of d6, etc). Or that the shadowcaster is largely emancipated from issues like casting defensively, or having his spells countered or dispelled, and gets a permanent, better form of the darkvision spell.
You can't just consider offense. Defense is a factor. If all we considered was offense, of course the glass cannon classes would always win.