Shanahan, whose Niners were immediately shut down when they inquired about Garoppolo at the NFL draft in April, told reporters his new quarterback became available right before the trade deadline - "to our surprise" - per Eric Branch of the San Francisco Chronicle.
Garoppolo was officially acquired from the Patriots on Tuesday in return for a second-round pick.
"We believe very much Jimmy will be our quarterback of the future," San Francisco general manager John Lynch said, according to Matt Maioco of NBC Sports Bay Area.
Lynch added that it took his organization just 10 minutes to agree to the trade.
"This is too good to not take advantage of," he said, as relayed by David Lombardi of The Athletic Bay Area.
That jersey is going to look good on you, @JimmyG_10👌 #GoNiners pic.twitter.com/NCldZHYTZi
— San Francisco 49ers (@49ers) October 31, 2017
Garoppolo, who's two days shy of his 26th birthday, is set to hit free agency at the end of the year, but Lynch noted the 49ers hope to work out a contract extension before then.
The Eastern Illinois product isn't expected to play this week, but should be ready to make his 49ers debut in Week 10 against the New York Giants.
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