Ericsson held off Pato O'Ward to score his maiden Indy 500 win, only his third in IndyCar competition after arriving from F1 in 2019, and the fifth for Ganassi's storied team since 2000.
Polesitter and 2008 Indy victor Scott Dixon had led for 95 laps but a pitlane speeding penalty dropped him out of contention and gave Ericsson the opportunity to become only the second Swedish driver after Kenny Brack in 1999 to triumph at Indy.
Ericsson joined Ganassi's team in 2020 from Arrow Schmidt Peterson Motorsport and became a race-winner last year, breaking his duck in Detroit before winning a chaotic race at Nashville.
Speaking after the race at Indy, where Ericsson gave the team its first 500 win since Dario Franchitti in 2012, Ganassi said that Ericsson had flourished after utilising the deep expertise within the team - including driver advisor Franchitti.
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“He's taken it upon himself to understand the resource in the team and understand how to use that,” said Ganassi.
“You just saw his career start to take off at the beginning of last season, once he understood what we were all about.
“This is the culmination of that effort.”
Ganassi explained that the factors which first attracted him to signing Ericsson were “no baggage, likes to go fast, just need to get him a good car basically”.
“Once he put his mind to that, the wins started to come, the consistency, the points started to come,” said Ganassi of Ericsson, who improved from 17th in his rookie year to 12th in 2020 and sixth in the standings last year.
“This type of experience [practice at the Indy 500] where you're out there testing a lot, practicing a lot, really suits his style.
“I think Mike O'Gara [strategist] said to me earlier that after the last pitstop, he didn't lift once, just held his foot to the floor and steered, [they] didn't have to make any changes to the car all day. They just put tyres on it. Tyres and fuel.
“You always hear that about the cars that win the Indianapolis 500. It's a clean day, they don't touch the car. Sure enough, they win.”
Ganassi also hailed the importance of teamwork between his five drivers in building a strong team for the 500.
Along with Dixon and Ericsson, reigning series champion Alex Palou led 47 laps, Tony Kanaan finished third and led six laps, while rookie Jimmie Johnson also led a couple of laps before his late crash.
“I just reflect on the past few weeks and the past few months of having these four or five guys around, working as one team, everybody cheering their team-mates on all the time,” said Ganassi.
“When someone on the team does something good, the other guys couldn't be happier, you know what I mean? That's what's so nice for me to have to deal with.
“You saw today we had different times of the race different cars in the lead. We came here at the beginning of the month wanting to win the race. That's, in fact, what we did.
“Nobody's happier than all the other drivers for the team winning.”
Team managing director Mike Hull echoed Ganassi in pointing to Ericsson's team attitude.
“What happens at Chip Ganassi Racing is resource,” he said. “Resource is all the people that work together.
“Chip said it best a minute ago. If you look at all the drivers we have, and have had over the years, they all have two or three things in common: no baggage is one thing, but the desire to win, be a team-mate and be unselfish. That's Marcus Ericsson.
“Now with the resource we have, he's very comfortable inside that resource.
“That's really the big difference, that's what we've seen.”
