Stewart had 25 retirements in their first year and one points finish (albeit a second place).
I'm leaning towards Tyrrell with Stewart as driver this time as opposed to team principle. As a customer team they took 3 wins (with Stewart) and 9 points finishes out of a 12 race calendar in 1968. Stewart was second in the WDC, he won it with them the following year.
At the back end of 1970 they had developed their own car, Stewart retired in each of the three races it entered, but qualified 1,2,2 before mechanical breakdowns. In the US, Stewart lead by up to half a minute before the Cosworth dumped it's oil and ate itself. The following year with their new chassis, Tyrrell would win 7 of 11 races and achieve double the points of their nearest challenger, BRM.
There is still an argument to say they weren't new though. How do you even define "new"? Haas are buying into Ferrari's parts bin and technology know how and no doubt they'll recruit from the 5000 strong existing F1 engineer pool. Is that really new?