MLB.com Columnist

Jonathan Mayo

Inbox: Breaking down Arizona Fall League prospects

Inbox: Breaking down Arizona Fall League prospects

The 25th anniversary season of the Arizona Fall League is now over a week old, and already a number of prospects are off to very strong starts. Having just returned from several days out there -- I've passed the baton to Jim Callis now, but will be back out for more -- I came away impressed with a number of players I got to see first-hand.

One of the things I love most about going to the Fall League -- aside from as much southwestern food as one can manage -- is seeing all these guys in one spot. And it's always a great combination of top prospects living up to hype or advanced billing (I'm looking at you Gleyber Torres) and under-the-radar types putting themselves more firmly on the map (more on some of them below). With more than enough to talk about, this week's Inbox is completely AFL-related. Enjoy!

More than anything, it's exciting to see Marcos Molina, currently ranked No. 11 on the Mets' Top 30 prospects list, back on the mound and healthy. Before starting for the Scottsdale Scorpions on Oct. 13, Molina had last thrown a competitive pitch in the Florida State League on Aug. 17, 2015. Elbow issues allowed him to throw just 44 1/3 innings that season and he missed all of 2016 following Tommy John surgery.

The right-hander has appeared twice thus far in the AFL and it's been so far, so good. In his first start, he was at 90-92 mph with his fastball and he mixed in his breaking stuff and changeup, allowing four hits, a walk and one run while striking out two over two innings. Molina was sharper in his second start on Oct. 19, throwing three scoreless while allowing just one hit and one walk and striking out one.

Getting innings is the most important part of his AFL experience, more than what the results are. The fact that he's been around the strike zone so much is a good sign. Still only 21, Molina was on a fast track before the injury as a young pitcher with outstanding command. There is more than enough time for him to return to climbing up prospects lists everywhere.

We here at MLB Pipeline certainly noticed what Isan Diaz did in 2016, his first year with the Brewers. At age 20, Diaz hit 20 homers to lead the full-season Midwest League and finished fourth in slugging percentage. While he struck out 148 times -- something he'll want to work on, for sure -- he also drew 72 walks, a sign that he's much more than an all-or-nothing hitter. That's why he's now in the Top 100 list (at No. 96).

In the AFL, Diaz struggled a bit so far, going 3-for-17 over his first four games. He has homered, though he's also struck out six times with no walks. It's a very small sample size, but it is very possible -- and understandable -- if Diaz is a bit on the tired side. He's coming off of his first taste of full season ball, playing 135 games and collecting 507 at-bats. Being able to push through the fatigue and continue to learn in the AFL will be good for his development as he moves up the ladder. That said, in BP, Diaz still was showing bat speed and strength. If he can show he can stick at shortstop -- most see him as a second baseman -- his stock could really go up. But even as a second baseman with that kind of bat, I'd expect him to move up a few notches at the start of the 2017 season.

Ramon Laureano is a prime example of one of those under-the-radar prospects who is making a name for himself thus far in Arizona. I got to see him a few times in that opening week and could not help but notice his approach at the plate and his swing. He deservedly was named the AFL Player of the Week.

Currently ranked No. 29 on the Astros Top 30, the 2014 16th-round pick is coming off of a very strong 2016 season that saw him hit .319/.428/.528 with 15 homers and 43 steals. Laureano was just one of two players in the Minors to hit at least 15 homers and steal 40 bases or more (Yoan Moncada was the other). He's hit .409/.440/.727 with three steals over six AFL games.

There is no question that if he keeps it up as he advances, he'll move up the Astros' list, and that 50 hit grade will have to be addressed. I think people will want to see him do it for longer at the upper levels -- he played 36 games in Double-A this past season -- and away from the hitting haven in Lancaster. That's especially true since he didn't put up those kinds of numbers during his first full season. His AFL performance shouldn't be over-counted, but it does add to the argument that he's really started to figure things out at the plate.

There has never been a question about Josh Staumont's stuff. He has an 80-grade fastball that touches triple digits consistently, and he has a very good breaking ball. His changeup, with splitter action, is more than usable. But that word you used -- command -- is what has held him back some. He did make it to Double-A in his first full season of pro ball, and moved from No. 18 on the preseason Royals' Top 30 prospects list to his current spot at No. 10. But he walked 104 in 123 1/3 IP, leading to many thinking he's better suited to the bullpen, where he definitely has closer stuff.

So far in the Fall League, Staumont has been as sharp as any arm, firing seven shutout innings across two starts. He's allowed just three hits and struck out five. But most interesting is the fact that he's walked only one batter. That by itself isn't enough to make everyone believe he can start, but when you combine it with the fact that he finished the year in Double-A so strongly in terms of cutting his walk rate down, then maybe you feel he has a chance. At any rate, it's fairly clear he should continue to work as a starter in 2017. If the Royals need relief help in 2017, then so be it. But to pull the plug on a starter who can throw 98-102 mph deep into starts would be a mistake at this point.

Jonathan Mayo is a reporter for MLBPipeline.com. Follow him on Twitter @JonathanMayo and Facebook, and listen to him on the weekly Pipeline Podcast. This story was not subject to the approval of Major League Baseball or its clubs.