Best examples that come to mind.
TJ dillashaw: as soon as he started working a lot with Duane Ludwig, his striking improved leaps and bounds.
GSP: After losing to Serra, seemed to gain some size, focused on the wrestling and grappling more, became more of a wrestler than before.
Chad mendes: after Aldo loss he was a straight wrestler, after the loss he became a knockout machine with 4 or 5 consecutive knockouts I think and the majority in the first round.
Fabricio werdum: joined kings and became a viscous striker, compared to when he first started was almost pure jiu jitsu.
Anthony Johnson:
Moved up from welterweight to light heavyweight joined blackzillians also improved his Dutch kickboxing and overall game leaps and bounds.
Vitor Belfort: joined blackzillions added more kicks to his arsenal, also got on testosterone replacement therapy
Tyrone Woodley:
was a pure wrestler before the Koscheck fight, turned to a knockout artist who bullrushed his opponents. After Rory loss became much more conservative only fighting in short spurts, to conserve his gas tank and stayed outperforming his opponents just enough to win fights. Attained smart fight IQ towards the later of his career.