Kind of, but Attack is also needed because of the somewhat decent damage that Sylvan units don't have; if the "Attack" stat were boosted instead of Knowledge, it would be great).
Machines for Sylvan... this question has always come up and has been discussed many times already, just like everything we're discussing now has been discussed before))

P.S.: Snezhok, decided to shake off the old ways?) HeroesWorld again, HoMM again!!11

I'm not saying that Sylvan doesn't need the "Offense" skill; that 15% would be very welcome, plus Ballista, plus another 20% to shooting. Lately I often take Leadership and aim for "Retribution"; if they also give "Aura of Speed", then magic races will be in a really bad spot :).

P.S. Shaking it off slowly :) HeroesWorld again, a bit of HoMM 5 again :)

2Ingvar
The secrets of Elven Kung-fu are revealed only to the persistent student :).
The mastery of clearing neutrals with the 1st fairy is known only to the chosen :).
But seriously—you're just used to playing as the Academy, and their tactics are very different from the Elven ones. More practice and it'll all come together :)