(CBS) The MLB First Year Player Draft starts tonight at 6 p.m., and both the White Sox (No. 3) and Cubs (No. 4) are in position to select elite prospects. Each also has its eye on pitching talent.

How it all plays out, of course, remains anyone’s guess, but below is CBSSports.com baseball insider Jon Heyman’s best guess after talking to league executives. If you want to see the entire first-round mock draft, click here.

1. Houston Astros

They may not be all that good at winning ball games yet, but they are very good at keeping secrets right up until draft day, as they did the past two years, when they used the No. 1 overall pick on Puerto Rico high school shortstop Carlos Correa, and then on Stanford right-hander Mark Appel. But the consensus seems to be the Astros will pass on almost major-league ready N.C. State left-hander Carlos Rodon and local 100 mph-throwing phenom Tyler Kolek to take excellent San Diego left-hander Brady Aiken, a polished high school pitcher. He’s said to be advanced, and with Rodon likely having a higher price tag, they just may take the mini gamble. High school pitchers going No. 1 have to this point disappointed greatly over the more than four-decade history of the draft. But there’s a sense Houston is undeterred.

The pick: Brady Aiken, LHP, San Diego Cathedral Catholic HS

2. Miami Marlins

They are said to love San Diego high school hitting star Alex Jackson, but the temptation to take Rodon, a Cuban star from Miami who can pair with Jose Fernandez and might even help in the second half would seem to be too great. Possesses a tough cutter (one scout likened him to Al Leiter) and “disappearing” slider. Word is, Rodon isn’t thinking about a discount, so the negotiation between Scott Boras, who’s advising Rodon, and the cost-conscious Marlins, would be interesting.

The pick: Carlos Rodon, LHP, NC State

3. Chicago White Sox

The flame-throwing Kolek, who also has very good secondary pitches, winding up here is seen as one of the rare near-locks of the first round. He’s a big kid (6-foot-5, 245) but he’s gotten himself into better shape and is said to have a nice feel for his pitches. The Cubs sure would love to grab one of the top three pitchers next, but their South Side rival is unlikely to give them that chance.

The pick: Tyler Kolek, RHP, Shepherd (Texas) HS

4. Chicago Cubs

With the top trio of pitchers likely gone, this is the real wild card of the draft. Chicago almost surely would have used this pick on a hard-throwing East Carolina righty Jeff Hoffman, who impressed Cubs honchos Theo Epstein and Jed Hoyer in his last performance before needing Tommy John surgery. They still could consider Hoffman, but it seems more likely they make a deal for another college star, and save some dollars. The need is pitching, but with the big three gone, they could go in any direction. There’s been some buzz they may go for mature Oregon State left fielder Michael Conforto, a power hitter who’s a safe bet, and also Indiana University catcher-outfielder Kyle Schwarber, who’s rapidly moving up boards. Hartford University left-hander Sean Newcomb, who’s been compared to Jon Lester, might intrigue Cubs scouting director Jason McLeod, who was part of the Red Sox contingent when Lester was picked there. Either way, it could be a deal that allows bolder picks later.

The pick: Kyle Schwarber, C-OF, Indiana

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