A few SU-27, Su-30s don't rule the skies.
Its an entire airforce the enemy will be against. Complete with
intelligence, combined-arms, C4i network, multi-layer,
multi-platform and more reliable and proven weapons, added to that
pilot skill and actual flying hour experiences and training with
the very best.
Anyway the F-15 is not a better dogfight, but it is a better BVR
fighter than the F-16 because of its better radar. In dog-fighting,
it just about matches the F-16 in performance.
The main advantage of the F-15SG is not in air-to-air, although
it is extremely capable. Its advantage lies in the ability to carry
a high payload (higher than F-16 or F/A-18), able to deliver it
long range, and still fight as a good air-to-air fighter.
That's like our multi-role F-16D/52+, but with even higher
payload, longer range and better weapons.