PEORIA, Ariz. -- It was a learning experience for the Nationals' Stephen Strasburg on Thursday at Peoria Stadium. In his second Arizona Fall League start for the Phoenix Desert Dogs, the No. 1 pick in the nation plummeted to earth.

Strasburg allowed eight earned runs and seven hits, including three homers (one a grand slam), in a 9-6 loss to the Peoria Javelinas. It was his first look at that kind of disaster. Take note that he gave up only 16 earned runs in 15 college starts this season for San Diego State, for which he was 13-1 with a 1.32 ERA during his junior year.

In his two AFL starts, he's 1-1 with a 10.50 ERA. Welcome to professional baseball.

Start No. 3 is slated for next Tuesday at 2:35 p.m. ET against the Peoria Saguaros at Phoenix Municipal Stadium.

"I felt pretty good, but I just wasn't able to work ahead in the count," Strasburg said. "I left some pitches up, and I know what I need to fix. Part of getting back into game shape is, you're going to have some good games and some bad ones. It's all about learning from it, and I feel I learned a lot from this outing."

Strasburg had only worked 8 1/3 innings since his final college start -- on June 1 to Virginia in a 5-1 loss at the NCAA baseball regionals. In addition, he was accustomed to pitching once a week in college -- every Friday. This was the first time the 22-year-old right-hander and San Diego native has been used in a five-day rotation, and it showed.

This past Friday night in Phoenix, adrenaline carried Strasburg through a 3 1/3-inning win, during which he allowed no runs on two singles, walked one and struck out two. On Thursday, in front of a crowd of 471, he seemed out of kilter right from the outset, although he whiffed four.

The second batter he faced, Jordan Danks, lined a single. With two out, Russ Mitchell and C.J. Retherford hit back-to-back homers, and suddenly, Strasburg was down, 3-0. Casper Wells hit a two-out slam to dead center in the third, making it 8-3. All of the homers came on pitches high in the zone. A batter later, he was pulled, having thrown his required 60 pitches.

Strasburg couldn't remember the last time he was struck for three homers in a single game, but it certainly wasn't during his last two collegiate seasons, when he became a national sensation as a starter after serving as the Aztecs' closer during his freshman season in 2007.

"I haven't faced professional hitters my entire life," he said in explanation. "I'm sure there were times in college when my stuff wasn't very good and I got away with it. These guys can hit mistakes. This isn't college baseball. These are Double-A, top prospects in each of their organizations. They can all hit and all have a plan out there."

Mitchell's homer came on an 0-1, 96-mph fastball. Retherford and Wells hit curveballs that hung in the zone.

"Those were the only two pitches I hung all day," he said.

According to MLB.com's Pitch F/X tracker, Strasburg topped out at 99 mph on the first batter, Lorenzo Cain, who struck out. He also threw two 98-mph pitches in that at-bat.

Even so, Strasburg said that he didn't trust his pitches. When asked what he learned about the pelting, Strasburg said:

"I learned that you've really got to trust your stuff. I came out today, and I really didn't trust it. I hit my spots well, and I wasn't getting the calls. So I tried to make an even better pitch rather than sticking with that spot and really working it. Bottom line is that I really need to go out there and trust in my abilities and let the chips fall. Today I got away from that, and I paid for it."