Nationals' skipper Dusty Baker before and after Reynaldo Lopez's MLB debut...

The decision to go with 22-year-old right-hander Reynaldo Lopez last night in the series opener against the visiting Los Angeles Dodgers came down to a choice between the Washington Nationals' top prospect Lucas Giolito, in what would have been his third major league start, or Lopez, who would be making his MLB debut.

Dusty Baker talked to reporters before the game about what went into the decision to go with Lopez, who started the season at Double-A Harrisburg, putting up a 3.18 ERA, a 3.14 FIP, 25 walks (2.95 BB/9) and 100 Ks (11.79 K/9) in 76 ⅓ innings pitched.

Lopez was then promoted up to Triple-A Syracuse, where he was (1-0) in two starts, posting a 3.27 ERA, a 5.50 FIP, six walks (4.91 BB/9) and nine Ks (7.36 K/9) in 11 innings before he was called up.

"In my understanding -- we had to depend on our minor league people for how he was throwing, because we didn't see him at all in Spring Training," Baker explained.

"He's a guy that has come fast. It shows how our minor league instruction is. It shows how his mindset was pitching at different levels and they said that he was throwing the ball great. If Giolito had pitched a little bit better this might not have happened. But the fact that Giolito was having trouble with his secondary pitches -- and in the big leagues if you're having trouble with your secondary pitches they'll just spit on that and just sit on your fastball. I don't care what kind of fastball you have.

"Plus, [Giolito] wasn't displaying excellent control with his fastball, so sometimes what we want, what we all want in the progress of certain players, it doesn't coincide sometimes."

So what did the scouting reports he received tell him about Lopez's command and offspeed stuff?

"The reports are that he can get away with more because he's throwing almost 100. That's exactly what the reports are. He might not have to be quite as fine when you're throwing hard like that."

Baker was asked if there were any limits on Lopez going into the outing?

"I'm hoping that he stays out of the big inning," Baker said. "That's what I hope. Guys are on a pitch count every day.

"They told me he's gone 100 pitches, I think, so I'm just hoping he's on a performance count. We need him to kind of go semi-deep in this game, because my bullpen is semi-rested."

Lopez did give the Nationals 105 pitches, but over just 4 ⅔ innings, He was hit hard and often early, falling behind 4-0 after two, before he settled in and put together a nice stretch.

Chase Utley took the right-hander deep on a 1-1 fastball on his third pitch of the game and eight of the first eleven batters overall reached base, but Lopez bounced back and retired eight straight to get through the fourth.

The Dodgers got to the righty again in the fifth, however, with a walk and two singles driving in their fifth run.

Yasiel Puig's two-out RBI single to center made it 6-0 LA and ended Lopez's night. In all, he gave up 10 hits and six runs while striking out nine of the 25 batters he faced.

"They didn't miss many fastballs and for a guy who's throwing as hard as he does you would expect them to miss more fastballs," Baker told reporters after what ended up an 8-4 loss.

"He had quite a few strikeouts, but most of his strikeouts were on his slider or his changeup. So you don't know if they were seeing something or whatever or maybe we weren't pitching inside enough or whatever, but the kid threw the ball pretty good. Surprisingly he had better command than I thought of the strike zone.

"I haven't seen the videos yet to see if they were in the heart of the plate or not, but we like what we saw and it was surprising that they didn't miss his fastball."

In spite of his struggles on the mound, Lopez remained calm and impressed his manager with his demeanor.

"He was pretty cool, especially in your first start, in the face of adversity, and being in trouble. I'm sure it shocked him right away to have your first big league hitter hit the ball out of the ballpark, cause I'm sure he's not used to guys catching up to his fastball. But he's young, this is the big leagues and you're facing big league hitters. I tell you his future is very bright. We've just got to tighten up a few things and I think he'll be here for a long time."

Asked if Lopez should have turned to his secondary pitches earlier than he did with the Dodgers squaring up his fastball in the first few innings, Baker said that would not necessarily have helped.

"Maybe location could have been a little better," Baker explained. "Because you want to establish your fastball first in order to make your breaking ball and your changeup better.

"They didn't really give him a chance to get to that breaking ball. They centered up and squared up that fastball ... you don't want him to go out there and right away pitch backwards and then get behind and then have to come back to the fastball. You have to give those guys over there credit for doing their scouting report and doing their homework."

Now it's up to Lopez to make the necessary adjustments if he gets another start with the Nationals.

Joe Ross, whose spot Giolito and now Lopez have filled, got through a simulated game yesterday, but will likely need a rehab start or two before he's ready to return to the rotation.

Will the Nationals turn to Giolito again, or give Lopez two starts as well before Ross is back? We talked about that and more on the latest edition of Nats Nightly: