It's impossible to get a true gauge on how well a guy is doing one month, the sample size is too small. That said, it gives a clearer look than the daily and weekly recaps that can fluctuate pretty wildly. I'll go alphabetically through the Hitters, then move on to Pitching.
Aaron Altherr - Altherr killed it in Clearwater while rehabbing, but he's struggled making good contact so far in Reading. Still a 4:3 K:BB ratio is a huge improvement so far. His line .210/.315/.387 isn't going to rocket him up prospect lists, but he's only been back a couple weeks. Give him a month to adjust and we'll see how he looks at the end of May.
Willians Astudillo - Not to be mean, but Willians is more of a curiousity than a real prospect at this point. That said, if he can keep hitting (a .424 BABiP suggests he won't) he could get some interest. He doesn't Walk or K, so he's always going to have an OBP really close to his BABiP (current BABiP .424, current OBP .415). So yes he looks great when he's lucky and the hits are dropping in, but if his BABiP adjusts you could be looking at a guy OBP'ing .290 and that will look much worse. He also doesn't really have a position. Still he hits and he can probably play as long as he wants in Minor League systems with his contact skills, just probably not enough to be a MLB regular.
Malquin Canelo - Canelo probably has the best glove in the system and has potential to be an elite Defender. His bat might be sub-Galvis level, but he's managing to hold his own mostly in Clearwater thanks to 3 doubles (all of his hits). 18 PA is too few to real draw any conclusions from, but since I omitted Canelo from most of my offseason writing, I figured it would be nice to shine a light on him here, as his glove alone could get him to the Majors in a John McDonald type role.
Zach Collier - I so want Collier to succeed. He's on the 40 man and every now and again you see flashes of his tools playing to potential. Then he shoves an ugly .173/.295/.231 line out there. His walk rate is good, but every other number is going in totally the wrong direction. One item in Collier's favor is that Tyson Gillies has been roughly just as inept at the plate and is two years older with an injury history, the verbal altercation with a bus driver and that weird arrest 2 years back, so if 40 man space is needed, I would bet on Gillies getting DFA'd before Collier. Still holding down the next to last spot on the 40-man is not the best of places to be. If he can figure it out, he becomes a younger, likely better version of Mayberry.
Dylan Cozens - Cozens, so far, is striking out way too often, walking way too little, but at least his contact has been pretty solid when he makes it. Cozens is never going to be a low K guy; he's simply too tall for that. That said he'll need to get it lower than 28.4%. His Walk rate, previously a strength, now sits below 5%. It may be that he's just adjusting to the level and those numbers will each rebound 3or 4 percent. Or it could be that he can't handle the Pitching as well at this level. Keith Law's scouting report on Lakewood leans to the latter, but Law really has disliked him some Cozens since draft day, so I'm not putting as much faith in that, as I usually do in Law's take on things (Law is a love/hate guy for lots of people, but I generally find his scouting reports the most accurate out there and he's right more often than not). I'll have my own take late this month when I play hokey from my day job to go watch Lakewood in Greensboro.
J.P. Crawford - I'll predict now that by the end of the season Crawford will be #1 on every Phillies list and a Top 50 overall prospect. His current .286/.394/.393 line is impressive on its own. Now look at his 15.2% K rate and 14.1% BB rate. That is fantastic for a guy two and half years younger than league average for the Sally. My bold prediction above assumes he makes Clearwater by season's end and succeeds there as well. Crawford's plate discipline has been light years better than I expected coming out of last year's draft and while he's racked up a few more errors than I'd like it's not alarming enough to think he needs to move off Short yet.
Kelly Dugan - Bad Luck Dugan has been hot at the plate, but he seems to keep getting odd unrelated injuries (this year he's been hit on the hand and pulled an oblique). His line of .275/.396/.375 with 16.7% K and 14.6% BB is every bit as impressive as Crawford's because Dugan is having that success in Double-A where he suddenly gained an odd immunity to Walks late last year (a Sebastian Valle like 2.2% BB rate). The sample is small because of almost 2 weeks missed to injuries and while his K:BB ratio is a great sign, he hasn't shown as much power this year, as his ISO is way down, along with his Line Drive rate and Outfield Fly Ball rate. We'll have to wait and see if those rates all rebound some in a larger sample.
Maikel Franco - Okay, the line looks awful (.172/.234/.253), but Franco is traditionally a slow starter and it's trending up from a low of .080/.148/.120 back on the 9th of April. This is much worse than previous slow starts, but remember that Franco was not only pushed up a level, but is also tweaking his swing. No need to panic, Franco will get the whole year to work out the kinks.
Zach Green - Another guy who lost time to injury and had mixed results when he did play. Green's BABiP was awful when he did play and his composite numbers suggest it was more likely bad luck than particularly weak contact (though his ISO looks remarkably terrible at .034 for a guy with some of the best power in the system). Similar to Dugan, Green hasn't played enough to really make much of anything from the numbers. I expect he'll be back in May and we'll be able to see if he had bad luck or if his slow bat is starting to catch up to him.
Samuel Hiciano - The triple slash of .259/.344/.383 isn't going to rocket him up propsect lists and his power hasn't really played in Lakewood yet, but Hiciano's a little young for the level (only slightly) and his plate discipline has been pretty good for a guy with his power potential. Now to get that power showing up more like it did last year.
Tommy Joseph - This one's tough to write up, honestly. Everyone raves about his leadership skills. He's good enough Offensively to have a future in the Majors, but he took a foul tip off the mask about a week ago and he's out with concusion like symptoms. He was off to a good start at the plate too, going .255/.333/.527. If he can't stay behind the dish, his bat won't play to prospect levels at First or in Left. There would need to be significant improvement as a hitter to remain a prospect.
Cameron Perkins - All he does is hit. Perkins is white hot, though the .438 BABiP suggests he'll cool. Here's the thing though, his Line Drive rate is so insanely high, that it's less luck that fielders aren't where he's hitting it and more that he's smoking the ball and those line drives naturally support a higher BABiP. I think it's likely his LD rate will drop and with it his .382/.427/.596 triple slash. I had previously thought of Perkins as a young Ty Wigginton, if he keeps this up, I may have to reconsider that.
Brian Pointer - Hey remember that time when I was tooting my own horn for predicting Brian Pointer's breakout? Let's all pretend that didn't happen. Current line: .190/.278/.329.
Carlos Tocci - I talked about Tocci a few days ago in my weekly recap, so I won't spend much time on him here. The .277/.303/.351 line are all really promising for an 18 year old in the Sally. That said, the 25% K rate and 2% BB rate are alarming. Neither are huge red flags just yet, but if he did that over a full season, even being young for the level I'd be very concerned and drop his stock. So far Tocci is making much harder contact and has almost doubled his ISO again. So, if he can get those K:BB ratios back to previous levels this would be a huge improvement.
Jesse Biddle - Through 6 games in 2014: 32.1 IP, 3.62 ERA, 27 H, 13 ER, 3 HR, 39 K, 12 BB and 1 HBP. Through 6 in 2013: 32.2 IP, 2.56 ERA, 13 H, 9 ER, 1 HR, 40 K, 16 BB, 0 HBP. Aside from hits and runs, that's a weirdly consistent trend. Not for the better either, per se. Errors haven't done Biddle any favors this year, as he's shot himself in the foot a few times when he could have escaped innings. He's still striking a lot of guys out and his walks are down so far, he needs to be a bit more consitent and with some luck avoiding errors he should show enough to make his way to Lehigh Valley in a month or two.
Percival Garner - You know there isn't much going on Pitching wise when Perci Garner gets written up. Garner likely is what he is at this point and can probably get moved to the Pen to see if he can get his stuff to play up. There are control issues that I don't think he'll get beyond enough to Start at higher levels, but he might prove a usefull Ethan Martin lite in relief.
Ken Giles - 13.0 IP, 1.38 ERA, 8 H, 2 ER, 25 K, 4 BB, 7 Saves. All 8 hits were Singles. Giles is dominating at Double-A, but he still has some tweaks to make in his control as he's getting swings he's unlikely to get in Triple-A or MLB. Still you can't argue with the results so far.
Severino Gonzalez - Sev's had an up and down month. Every Pitcher has bad starts and Sev is in a rough patch currently, but his overall numbers for the month are pretty solid: 34.1 IP, 3.67 ERA, 34 H, 14 ER, 26 K, 7 BB and 2 HBP. Sev is a control artist with no overpowering pitches, so the 9 free passes (including HBP) is not a good sign. I'll admit I was never a big fan of Severino and I listed him much lower than others. He's handling Reading fairly well so far and I'll happily eat crow if he stays fairly successful all year. As with everyone, this is too early to make many certain call though.
Mark Leiter, Jr. - Leiter's a little old for Low-A, and honestly, the Clearwater rotation is so utterly abysmal they could use a guy who can succeed in a Starter role there. Scouts (including the aforementioned Keith Law) will tell you Leiter's probably just a nice Org. arm and they're probably right, but Leiter knows how to pitch well enough that it's not out of the question to hope maybe he can work his way to the back on an MLB rotation or work his way into a bullpen spot. He doesn't have the raw stuff to be a star, but he might be smart and good enough to work his way into a role in a few years. Not bad for a guy picked in the 22nd round.
Ethan Stewart - Stewart got some press this month (albeit misidentified as Ethan Martin) for a string of quality starts. That said, in spite of his 3.18 ERA and having been saddled with a rather insane 9 unearned runs, Stewart was not very good. 34 IP, with 15 K, 17 BB, 1 HBP, 6 HR, 7 doubles and a triple is a pretty awful set of numbers.
Tyler Viza - Viza was a 32nd Round pick last year who projects a bit better than that tag line makes it sound. He got a bit of a late start this year, but 5 appearances in he has 29.0 IP, 3.72 ERA, 30 H, 12 ER, 15 K, 5 BB, 1 HR, 9 doubles and 4 triples against. The control is pretty good, but there's a lot of hard contact there. Still, this was a 2 level jump (not common for a 32nd round High School pick), so I'm willing to give it some time to see how he adjusts.