According to Adam Rubin of ESPN New York, Terry Collins prefers to use Willie Harris as the Mets’ Opening Day left fielder.

Jason Bay will begin the year on the disabled list and won’t return until April 9 at the earliest.

The Mets will carry young slugger Lucas Duda in Bay’s spot and will expect Duda to start most of the games in left field.

If so, why does it seem that Harris will get the Opening Day nod?

Harris has had a productive spring and rightfully earned a spot on the roster. He showed some pop over the last few weeks and should be a versatile member of the Mets’ bench.

Even so, you might still be asking why the Mets will start Harris when they want Duda to play every day.

The answer is simple: The Mets will be facing Florida Marlins’ ace Josh Johnson—one of the top pitchers in the game—on Opening Day.

Rather than have Duda start the season with a tough outing against Johnson that could crush his confidence, Collins can save Duda for Game 2 against Ricky Nolasco. Though Nolasco is no slouch, Johnson can be unhittable at times.

If the Mets do go with Harris on Opening Day like it seems, the lineup may look similar to this: Reyes, Thole, Wright, Beltran, Davis, Pagan, Harris, Emaus.

As Rubin reported, Collins may want to use Pagan as more of a run producer rather than a table-setter in Bay’s absence. This lineup could do some damage and has a nice combination of speed and power.

While Harris has done everything to earn the spot in the starting lineup, why is Scott Hairston not being considered?

Hairston had a monstrous spring training for the Mets. He hit .345 with four HR and 12 RBI in just 58 at-bats.

Though the games don’t matter, Hairston hit some clutch home runs this spring.

The one drawback from Hairston this spring has been his strikeouts. While he showed good power, he struck out 14 times.

Against a power pitcher in Josh Johnson, the Mets must focus on putting the ball in play and force the Marlins to make plays. The fish have been known to play shoddy defense, so the Mets must capitalize on their mistakes.

Harris is more of a contact threat than Hairston. He can use his speed to manufacture runs, which will be key against Johnson.

Additionally, having the power threat in Hairston available to pinch-hit late in the game can work to the Mets’ advantage. The Mets may need an extra base-hit to start a rally, and Hairston can provide that punch.

Though I’d like to see as much of Lucas Duda as possible the next week and a half, I agree with Collins’ logic here. Allowing Duda to not be overmatched in his first game of the season can go a long way in his development.

Another question you may be thinking about is the following: What happens if Duda absolutely rakes in Bay’s absence?

He would really have to show some good power and drive in a ton of runs early for the Mets to even consider keeping him with the big club. Still, no matter where he is, Duda needs to play every day, especially defensively, to continue improving.

Burying Duda on the Mets’ bench would do him no good. While Carlos Beltran won’t be expected to play every single game, Duda would still have to battle Harris and Hairston for playing time.

These questions and more should be answered as the season progresses.

I’m sure you’re as excited as I am for Opening Day tomorrow. Here’s to a lot of fun in 2011. Win or lose, it’s great to finally have baseball back.

Follow me on Twitter @JMMancari.