It's just about holiday time for much of us. The first night of Hanukkah and Christmas Eve coincide this year. That's not quite as exciting as Thanksgivukkah a few years back, but still nifty timing by the two different calendars, no?
I haven't had enough time to go gift shopping for all of you. The best I can do is to answer some of your questions in this week's edition of Pipeline Inbox. Best thing about it? Doesn't take up a lot of room under the tree or by the menorah! Enjoy!

For now, Dunning is known as the "other guy" in the big Adam Eaton trade from the Winter Meetings. It makes sense given that Lucas Giolito and Reynaldo López, both currently in the top 40 of our Top 100 Prospects list, were the headliners in the trade.
That doesn't mean anyone should sleep on Dunning. The No. 29 overall pick in the 2016 Draft, Dunning was part of a ridiculously stacked Florida Gators pitching staff. It was so deep that Dunning couldn't break into the rotation -- he was also deemed too valuable pitching out of the bullpen to remove from that role. But he profiles very well as a starter in the future. He has size (6-foot-4) and good stuff (he should end up with three average or better offerings) and could be a workhorse in the middle or back of a roation.
Now, anyone who knows me knows I am not a big fan of MLB comps. I find them too forced more often than not. Sometimes you match the stuff, but not the body. Sometimes it's the other way around. But it's the holiday season and I'm in a giving mood. The comp I've heard for Dunning that might fit your "if he reaches his ceiling" question best could be John Lackey.

Right now, it's the only game in town, right? I think the very general answer is that performances in winter ball are valuable, but all should be taken with a grain of salt.
Much of that salt is because of sample size more than anything else. Sure, an everyday player can rack up a good amount of at-bats, but it's not like it's a full season's worth of data to consider. Some of it is because of the level of the league, as you asked about. Each league is different, with the Dominican Winter League generally considered to be the best. Especially as leagues approach the playoffs, you'll see more big leaguers get involved.
More than anything, what makes performances in the Winter Leagues in the Dominican Republic, Venezuela, Puerto Rico and Mexico valuable is the focus on winning. The Arizona Fall League is great, and players there no doubt play to win, but it is, first and foremost, a developmental league. In the Winter Leagues listed above, it's all about winning. Games are played in front of packed houses of very involved fans. Success in a league can lead to playing in the Caribbean Series. Seeing how a young prospect deals with that kind of spotlight and pressure can tell more about his future than whatever numbers he puts up.

If you were to look solely at his stuff, you might be inclined to say yes, he has a chance. But his size, combined with some concerns about effort in his delivery (though that's improved), probably mean he won't be seriously considered for the top spot by the Twins.
Based on his outstanding fastball and slider, not to mention his improving changeup, the North Carolina right-hander was ranked No. 6 on our recently released Draft Top 50, the third-highest college pitcher in a class that is particularly deep in that category. Even though there is some effort, he does have solid command, leading more to believe he can start long term, even if his size and the delivery have some worried about durability and thinking of a career as a closer. Because he's just six-foot, he's drawn comparisons to college arms like Sonny Gray and Carson Fulmer. Gray went 18th overall in 2011 and his fellow Vanderbilt alum Fulmer went No. 8 in the 2015 Draft.
I had a scouting director tell me recently he thought the bias against "undersized right-handers" had dissipated somewhat, so there might be more teams willing to consider someone like Bukauskas. Maybe that means he lands in the top five if he pitches well this spring, but I'd be surprised if he ends up in conversations for that No. 1 selection. 

Good timing for this question, as we've begun work on our 2017 Top 100. If we could go back to the preseason 2016 list, two choices jump out. The first is Nationals outfielder Victor Robles, who was No. 63 at the start of last season. The other is Mets shortstop Amed Rosario, who was at No. 79. When we re-ranked in July, however, they were moved way up and currently stand No. 10 and 11, respectively.
Typically, I'd look for a young and ultra-toolsy prospect who is far away, with the thought that if said prospect reached his ceiling, he'd climb to No. 1. The one name that really makes sense to me is Kevin Maitan of the Braves. The shortstop just signed out of Venezuela this past July 2, for $4.25 million. He might be a third baseman eventually, but he's been compared to Miguel Cabrera and Chipper Jones. He's No. 89 right now, but will likely make a large jump in 2017 and is just the kind of guy who could land in the top spot if he's as good as advertised.