Magnussen was embroiled in a ferocious battle with Lewis Hamilton throughout the 19-lap encounter.
The pair were scrapping over the final points-paying position with the Haas driver also defending to protect team-mate Nico Hulkenberg in seventh.
In defending against Hamilton, Magnussen thrice ran off the road and maintained position – in one instance, re-passing the Mercedes having been off track.
“The penalties were well-deserved, no doubt about it,” Magnussen admitted to Sky Sports.
“But I had to play the team game again.
“I was in a very good position behind Nico there in the beginning f the race, I gained a lot of positions, was up in P8 and protecting well from Lewis because I had DRS from Nico.”
It was when Magnussen lost DRS to his team-mate ahead that he became vulnerable to Hamilton behind.
“I had good pace, I felt, but Nico cut the chicane and I lost DRS.
“Nico could have given that back, so to give me the DRS to protect, because then we would have easily been seventh-eighth.
“Instead, I was really vulnerable to Lewis, started fighting with him like crazy, and then I just had to create the gap like I did in Jeddah.”
In Saudi Arabia, Magnussen backed up the field behind him to protect Hulkenberg ahead as he occupied the final points-paying position.
His efforts proved effective as Haas scored its first points of the year.
Repeating that effort in Miami helped Hulkenberg secure another two points, taking the team’s tally for the year to seven, while Williams, Alpine, and Sauber are all yet to get off the mark.
“I started using these stupid tactics, which I don’t like doing, but at the end of the day, I did my job as a team player,” Magnussen said of his antics in the Miami Sprint.
“Nico scored his points because I got that gap for him so Lewis and [Yuki] Tsunoda couldn’t catch him.
“Not the way I like to go racing at all, but what I had to do today.”
Magnussen picked up three 10-second penalties in the Sprint as well as a five-second penalty, dropping him to 18th – the last classified runner.
Ironically, Hamilton was also penalised post-race with a 20-second penalty for speeding in the pit lane, which demoted him from eighth to 17th, allowing Tsunoda to claim the final championship point instead.
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