Grandpa Pitcher Aiming to Be Rare MLB Player

— -- A 40-year-old former professional baseball player says he hopes to make a grand comeback as one of the few grandfathers to have ever played in Major League Baseball.

“I’ve been asking sports columnists if there have already been any, but we haven’t figured that out yet,” said Mark Hendrickson, whose resume also includes the NBA. “If not, I would like to be the first.”

It turns out Julio Franco was a grandfather as a 49-year old active player before his last game in 2007 with the Atlanta Braves, according to Major League Baseball.

Hendrickson, a former Orioles pitcher, practiced in a Florida minicamp hosted by the Baltimore team Monday and Wednesday, using a new sidearm delivery.

He says he’s “optimistic” he will be invited to practice with the Orioles in spring training next month.

Hendrickson, who became a grandfather to his first granddaughter two months ago, said “age is nothing but a number.”

And if he makes it to the team, he wouldn't be the only grandfather to have played in the major sports leagues. Former NFL quarterback Brett Favre became a grandfather in April 2010 at age 40 and filed retirement papers with the NFL in January 2011. Gordie Howe was a grandfather when he retired from the National Hockey League's Hartford Whalers in 1980.

Hendrickson lives in York, Pennsylvania, only an hour north of Oriole Park at Camden Yards. His goal is to continue performing at a “high level.”

The father of three daughters said it has been a “steep learning curve” to be surrounded by even more women, coming from the testosterone-heavy environment of professional sports. His wife and daughters, 22 months to 20 years old, completely support him, he said.

The 6-foot-9 southpaw delayed his major league debut until 2002 because he was playing in the NBA from 1996 to 2002. Out of high school, he was drafted in the 13th round by the Atlanta Braves in 1992, but he chose to go to college instead. He then played basketball and baseball at Washington State University.

After graduating college, he was picked up by the Philadelphia 76ers in 1996, the year Kobe Bryant was drafted by the Lakers, and later had stints with the Sacramento Kings, New Jersey Nets and Cleveland Cavaliers.

Since Hendrickson’s last appearance with the Orioles in 2011, he has never “stopped playing,” he said.

“All my life, I played basketball in the winter and baseball in the spring,” he said.

Before he played with the Orioles, Hendrickson’s baseball career brought him to the Tampa Bay Devil Rays, Los Angeles Dodgers, Florida Marlins. He played in the Orioles’ minor-league system in 2013.

After Baltimore manager Buck Showalter suggested the sidearm delivery pitch, Hendrickson asked him for a chance to make the team.

The Orioles declined to comment to ABC News when asked for their reaction to Hendrickson’s practice and whether he might be invited to train next month.

Though Hendrickson admits he is “reinventing” himself, both he and the Orioles haven’t technically called the minicamp a “tryout” or audition.

“[The Orioles] know me," he said, "and I know them."