McCullum said Iyer's has been "incredible story" after the lanky southpaw from Indore amassed 370 runs from 10 games in IPL 2021.
Kolkata failed to capitalise on a great start in reply to Chennai's 192/3 as the MD Dhoni-led side powered to a fourth IPL title in Dubai.
The cryptic post also built speculation around which franchise the Australian opener would prefer if given a choice in the upcoming season.
From a comfortable position of 96/1, KKR dragged themselves into a difficult situation in the end. They will play CSK in the final on Friday.
Narine, who had to remodel his action after coming under the scanner due to a suspect action multiple times, singlehandedly eliminated Royal Challengers Bangalore with bowling figures of 4 for 21.
Sanju Samon's side has exited the tournament finishing seventh in the points table.
KKR are currently the front-runners in the race for the final spot.
Mohammed Siraj was the previous fastest Indian bowler in IPL with a delivery clocking 145.97 kph.
Shubman Gill top-scored 57 from 51 balls as Kolkata chased down Hyderabad's modest total of 115/8.
Chris Gayle misses out for Punjab while KKR has brought in Tim Seifert replacing Lockie Ferguson