Happy New Year, prospect fans!
As we kick off 2019 together, we here at MLB Pipeline are ready to once again bring you all the prospect news that's fit to print. We're working on our new Top 100 prospects list, set to come out at the end of this month, introduced by our Top 10 by positions lists. (With, of course, brand new Top 30 team lists after that.) Before we know it, we'll be reporting from Spring Training camps every day.
The Pipeline Inbox has become a mainstay in our weekly lineup of coverage and that's certainly not going to change any time soon. So dig in to the first '19 edition of the Inbox and make a New Year's resolution to send in good questions all year long. 

Two caveats I have to throw out before I dig into this question. The first is that, as a Pittsburgh resident, I have to be careful here and am very mindful about not being a homer, while also not swinging too far in the other direction. The other qualifier is that I'm using the top five prospects rankings as they currently are on Prospect Watch, lists that we will be updating in the coming months. Now, with that out of the way, here we go.
I've listed the top five for each organization, ranked by how I would line them up.
1. Reds: Nick Senzel, Taylor Trammell, Hunter Greene, Jonathan India, Tony Santillan
2. Pirates: Mitch Keller, Ke'Bryan Hayes, Travis Swaggerty, Oneil Cruz, Cole Tucker
3. Cardinals: Alex Reyes, Nolan Gorman, Dakota Hudson, Ryan Helsley, Andrew Knizner
4. Brewers: Keston Hiura, Corey Ray, Brice Turang, Lucas Erceg, Tristen Lutz
5. Cubs: Miguel Amaya, Adbert Alzolay, Alex Lange, Brailyn Marquez, Aramis Ademan
It's close at the top for me, but the Reds currently have four guys on the Top 100, while the Pirates have just three. The Senzel-Trammell-Greene trio, all in the top 25 overall, is tough to beat, as good as Keller and Hayes are at the top of the Pirates' list. If Reyes comes back healthy in 2019, he and Gorman make for a formidable 1-2 punch on the Cardinals' list, though Reyes will also graduate the second he records a big league out. (He is at 50 IP for his career, and we graduate prospects once they get past that rookie-eligible threshold.)

I've had many conversations with scouts about how shifting has changed the evaluation process, but honestly, most of them haven't been about hitting. I could see an argument being made that someone with power and launch-angle abilities could have more value, because hitting the ball over the fence is the easiest way to beat a shift.
Most discussions I've had about shifts have been more about what they do in terms of evaluating talent defensively. Obviously, range/quickness, hands and how you throw are still important. But there is some chatter about whether a player profiles as a "true shortstop," for example, matters as much as it once did. I think the consensus would be that a player who fits that profile still is very valuable, but when you consider that a shortstop might end up playing on the right side of the infield quite a bit, or as the only player on the left side, via a shift, drafting a player with perhaps a touch less range, but a solid offensive profile, might be more acceptable. It also used to be that a player who didn't profile at one specific position might not be viewed as positively. A player who looks like a super-utility type at the start of a career was not valued as much. But I have to wonder if the increased importance of positional flexibility -- top prospects like Nick Senzel and Brendan Rodgers will likely break in to the big leagues by moving around defensively -- will filter down more to amateur scouting. And the fact that every team uses shifts of some sort now only has to bolster that concept, right? An ability to play different spots on the infield has to be a plus given the different configurations teams use these days.

I'm not entirely sure what's going on in Mets-land to elicit two questions about Vientos, currently No. 8 on the Mets' Top 30. Maybe it's because of the recent trade that sent two of the prospects to the Mariners, so fans are now looking at who else might be coming.
Whatever the rationale, Vientos certainly is intriguing. He's moved slowly, spending two summers at rookie levels, but he certainly improved from his summer debut in 2017 to the year he had in the Appalachian League last season. The big, strong and projectable third baseman finished third in the circuit in RBIs, tied for fourth in homers and landed in the top 10 in both slugging percentage and OPS. And as he continues to fill out his 6-foot-4 frame and learns to use his bat speed more consistently, there's definitely more power to come. We'll have to wait and see how the hit tool plays as he moves up the ladder, but his willingness to take walks will certainly work in his favor. A move to full season ball will be a nice test for Vientos, but I could see him becoming a big power-hitting run producer at the hot corner in a Troy Glaus kind of mold if it all clicks.

Medina is currently No. 3 on the Phillies' Top 30 and No. 64 overall. The right-hander is coming off a solid season in the Florida State League, though his ERA looks inflated thanks to a small amount of really bad outings. The stuff, three pitches that could be above-average to plus when all is said and done, is still really exciting. And he throws strikes with all of them.

Whether or not that makes him "centerpiece" worthy might be in the eye of the beholder, but my gut tells me Medina isn't the kind of elite-level guy right now who can dominate a trade to bring in the kind of premium big leaguer you're working for. Luckily for the Phillies, there are other players who could be included with him to perhaps fetch that return. Obviously, Sixto Sanchez, the team's top prospect, is that kind of player, but he's also coming off of injury and is someone the Phillies, or their fan base, might not want to see go. Now, if Medina moves up to Double-A and shows he can dominate advanced hitters, while pitching in a hitting-friendly Reading ballpark in 2019, then that could move him into a different level of prospect status. It could mean he'll be ready to help out in Philly later in the season, or it could be that he's moved to the kind of prospect level that does indeed make him "centerpiece" worthy.