knows their stuff
- expertHighly skilled practitioner
- skilledHaving learned ability
- competentSufficiently able, qualified
- proficientHaving practiced ability
- savvyPractical shrewdness
knowledgeable · seasoned · veteran · master · guru · whiz · sharp · capable · adept · specialist · pro · ace · wizard · virtuoso · craftsman · authority · insider · experienced
competence/expertise
knows their stuffincompetent
Lacking necessary skill
clueless · in over their head · unqualified · inexperienced · amateur