As we turn the calendar to September, MLB teams can expand their rosters. We'll see some minor-league depth come up, we'll see players return from injury without necessarily having to displace a player on the roster and -- the most exciting part -- we'll see some prospects. The top one is coming, too.

The Red Sox announced on Wednesday night that infielder Yoan Moncada will join the team from Double-A Portland on Friday.

Here are four things to know:

1. His talent is off the charts

He was ranked as the top remaining prospect in baseball by Baseball America in their midseason update. The Cuban defector is only 21 and has only been stateside for just two seasons.

In 105 games between high Class A and Double-A this year, Moncada has hit .298/.411/.518 with 31 doubles, six triples, 15 homers, 61 RBI, 94 runs and 45 steals. He's also known for a great glove at second base and has a good enough arm to handle third. We're talking about true five-tool potential here.

Moncada has struck out 122 times in 400 at-bats, but the 72 walks are encouraging with that.

2. We've seen Moncada win an award in a big-league stadium recently

Remember the Futures Game in San Diego's Petco Park the Sunday before the All-Star break? Moncada went 2 for 5 with a late go-ahead home run:

It was good enough to take MVP honors.

3. Moncada could be the answer at third base

We know at second the Red Sox have this dude named Dustin Pedroia and he's pretty good. Moncada was long pretty much only a second baseman.

Over at third, it would appear that Moncada could serve as an upgrade, because a Travis Shaw/Aaron Hill platoon isn't exactly tearing things up at the moment.

And wouldn't you know it, Moncada started at third in Double-A on Aug. 12 and has done so in every game he's played since. He has made three errors in only three chances, so there might be some growing pains, and he might not play everyday.

Let's keep in mind there might have to be a transition period here. Moncada is a supreme talent, but he hasn't even had 200 at-bats above the Class A level yet. It's possible he struggles at the plate and defensively here at first.

4. The Red Sox eased in Xander Bogaerts this way

It wasn't the same front office, but manager John Farrell was also at the helm in 2013 with Bogaerts in a similar situation. It's not identical, because Bogaerts actually got the call on Aug. 20, but he was only 20 and got some time out of position at third base.

Bogaerts ended up playing a key role on a World Series champion and the Red Sox look like a decent bet to make the playoffs this time around.

One big difference? Bogaerts wasn't the base-stealing threat Moncada is. He had only seven steals before getting the call in 2013. So maybe we see Moncada pinch run more than Bogaerts did.

But maybe we see him just take the third base job and run with it. It'll be fun to watch unfold. The top prospect in baseball is getting the call.