With the skill tree revamp Sensor Scan & Fire on My Mark got a "Sensors Skill" dependence, but the damage resistance component haven't been affected. Instead, both damage resistance component got an 75% boost.
Photonic Fleet is an another example, but instand of 75% ability boost it only get 50% Boost.
but sensor scan itself got a massive nerf on its defense reduction.
Originally Posted by mancom
Frankly, I think the only sound advice that one can give new players at this time is to stay away from PVP in STO.