Michael Ynoa threw his first professional pitch this year, but it also appears that the 18-year-old righthander has thrown his last pitch of the year as well.

Ynoa, who sign with the Athletics for an international record $4.25 million in 2008, is scheduled to have elbow surgery on Aug. 24 that is expected to be Tommy John surgery, according to several tweets from reporters out of Oakland. The procedure is expected to cause him to miss the entire 2011 season.

Ynoa was scheduled to make his pro debut in 2009, but he missed the entire season with elbow tendinitis. He made three starts this year in the Rookie-level Arizona League, allowing five runs in nine innings with four walks and 11 strikeouts, and reports were that he had been clocked up to 95 mph before getting hurt.

The injury could also make for an interesting decision in a couple of years. Ynoa won't pitch next year, but the A's will have to decide whether to protect him from the Rule 5 draft after the 2012 season. At that point, even in a best-case scenario, Ynoa will likely have only pitched at the low Class A level in his first year after surgery, assuming no further setbacks.