Andrew, a good question about Xavier Paul.  I disagree that I ranked him "highly."  I mean, he is behind Stults and Young, so he is definitely down among the guys you would expect to be long-shots to have MLB careers.  

I will get into the scouting stuff, which is more important to me, in a second.  You are more interested in the stats, so we'll take a look at that angle first, and you also bring up age.  You say Paul is not "particularly young," but Paul was still "young," being 21 in a league where 22-shading-toward-23 is average.  Chase Utley hit .257/.324/.422 in the FSL at age 22, so you can compare that to Paul's .285/.343/.430.  Adjust for the age difference in one direction, and in the other direction adjust for the fact that Paul's home games were in a more hitter-friendly park, and the performances might come out in the same neighborhood.  Also, take note of the differences in Paul's stats against lefty and righty pitchers.  While managing only a .247/.307/.370 line against southpaws, Paul hit .293/.351/.442 against righties, which is not outstanding against righties, but is enough to think there may be a future in this game for the guy. If a lefty hitter can hit righties, MLB teams are pretty tolerant of futility against lefty pitchers. That's what platoons were made for.

Now for the scouting perspective.  I'll come right out and say it:  Paul is a poor man's Matt Kemp, scouting-wise.  On the positive side, Paul has excellent bat speed: his swing is whip-like, short to the ball, and he finishes high, so the ball carries well when he makes contact. In the outfield, his arm is a cannon, and his throws are very accurate.  Paul also has plus running speed. On the negative side, Paul has poor pitch recognition, which leaves him too often guessing at the plate.  Fielding can be an adventure for Paul because he gets poor reads and jumps on flies, negating much of the value of his speed in the field.  The value of his speed on the basepaths is also compromised by poor base-running technique.  Now the positives and negatives I just listed mirror the positives and negatives of Kemp for the most part, if not entirely.  In other words, the tools are there, they just need to be turned into baseball skills.

Kemp and Paul are the same age (well, Kemp is about five months older).  They were drafted the same year, Paul in the 4th round and Kemp in the 6th.  Has Kemp moved faster, and does he appear to have a brighter future?  Absolutely, which is why I ranked Paul only #19 while if Kemp were still prospect-eligible I would have ranked him #1. But honestly, can we really say that Kemp has made faster "progress" than Paul turning his tools into skills?  I am not so sure.  Kemp still looks like he is learning the game of baseball in so many ways.  I think that the fact that Kemp's tools come in a 6'4 body while Paul's come in a 5'10 body has made it possible for Kemp to buffalo his way through the minors in a way that a smaller and obviously weaker man can't, without refining his tools.  (The 6'4 Jeff Francouer buffaloed his way to the majors quickly the same way, despite the fact that his baseball skills are still raw.)  Also, Kemp's being a right-handed hitter has meant he has not had to worry about the handicap that so many young left-handed hitters face because they are just not used to batting against same-handed pitchers.

I hope I have answered your question about Paul to your satisfaction, if not persuaded you of his merits.  I won't be surprised if Paul doesn't make it to the majors, as guys who rank #19 in a particular system usually don't.  But I do see some potential for an MLB career there, possibly as the lefty side of a platoon, and very likely for a smaller market team than the Dodgers.

Sorry to disappoint you, Andrew, but I made my list quite a while ago, and while I have revised the list a few times since the end of the minor league season, because of new information or just changes of mind, Bastardo has been #30 for a while. He had a good K rate, but a few more walks than you want from a 22-year-old in high A. He is also short for a pitcher.  But like I said, he places where he does because of how much I DON'T know about him.  I am open to the possibility that he should rank higher, depending on what we eventually learn about his stuff.  I am hoping Bastardo makes the next Baseball America Prospect Handbook, and I plan to ask the BA writer a question about him in the "chat" that will be done for the Dodgers' farm system in mid-February.  If Bastardo's fastball stays in the 90's over multiple innings and he has a good breaking ball, I will like him a lot more than I will if I find out he is just a soft-tosser who has been fooling Single A hitters.  At any rate, like you I LOVE his name, so I will root for him to make the majors as a Dodger even if he IS a soft-tosser, but his chances of ever being a Dodger are going to go down tremendously if he is a finesse pitcher and not a power guy.

I think Logan White very much had Kemp in mind when he drafted Mattingly.  The similarities at age 18 are very significant:  big and strong athletes very fast for their size, and more noted as high school basketball players than baseball players.  White must have thought that if Kemp worked out really well, why not try and duplicate the success by procuring a very similar athlete?  I guess what some people would question is using a first supplemental pick and a $1 million signing bonus on this kind of player.  Matt Kemp was a 6th rounder who received a $150,000 signing bonus.  If Kemp had flopped, people would say White took a risk in the 6th round and not much was lost with the failure of the pick, because few 6th rounders ever make the majors anyway.

At any rate, Mattingly definitely qualifies as a "high risk, high reward" prospect, and if in ranking prospects "potential" is an important criterion for you, then Mattingly certainly deserves a high ranking.  But if in making rankings of Dodger prospects you regard "proven production" and "closeness to the majors" as more important than potential, then you are not going to be that big on Mattingly -- at least yet.