Before the season started, I compiled the top 20 prospects lists published from Baseball America, Baseball Prospectus, and MinorLeagueBall.com into a single top 20 prospect list. Below is the order of that offseason prospect list ranking with a mid-season update on how the prospects are progressing.

1. Devin Mesoraco – C (.214/.295/.393)
Devin Mesoraco has been with the Reds since opening day as the back-up catcher to Ryan Hanigan, typically catching 2 out of every 5 games. Mesoraco had a hot start to the season with a .300 AVG and .822 OPS at the end of April, but has struggled the past couple of months. Devin will start the second half of the season in the midst of a modest 5 game hitting streak.

2. Billy Hamilton – SS (.323/.411/.443)
Hamilton was promoted to AA this week after his appearance in the Futures game. He has already stolen 105 bases in 83 games. The bat is there. The speed is there. The question is whether his defense will improve at shortstop or will he eventually be moved to another position.

3. Zack Cozart – SS (.252/.298/.409)
In his first full half season, Cozart has a league average OPS for a shortstop and has more than held his own defensively. A poor May has sunk his overall line. Since May 31, Cozart has hit .273/.320/.420, and starts the 2nd half having hit safely in 6 of his last 7 games.

4. Daniel Corcino – SP (6-4, 3.16 ERA, 1.255 WHIP)
Corcino has taken all 17 of his starts for AA Pensacola, and at this pace could find himself in the Reds sometime in the 2013 season.

5. Robert Stephenson – SP (0-0, 2.18 ERA, 1.161 WHIP)
Stephenson made his professional debut with Billings in June. Through his first 5 starts, Stephenson has thrown 20.2 innings, allowed 16 hits, 8 walks, and struck out 24 batters.

6. DiDi Gregorius – SS (.278/.344/..373)
Gregorius is the third shortstop prospect in Cincinnati’s top 6, and the best of the trio defensively. With his and Hamilton’s promotions this week, all three of these Reds pre-season SS prospects are at the AA level or higher.

7. Todd Frazier – 3B/LF (.278/.345/.556)
It doesn’t seem like it, but Todd Frazier had the majority of the Reds starts at 3B in the first half, putting up a better first half slash line than super hyped prospect Bryce Harper.

8. J.C. Sulbaran – SP (6-6, 4.22 ERA, 1.506 WHIP)
Sulbaran has shown flashes of talent for AA Pensacola, but has not yet strung together strong starts consistently.

9. Neftali Soto – 1B (.236/.293/.380)
Blocked by Joey Votto at the major league level, Soto is having a rough season at AAA, so far.

10. Henry Rodriguez – 2B/3B (.325/.363/.422)
After playing the first month in AA, Rodriguez spent almost 2 months on the DL with a broken thumb. He just returned last week and was promoted to AAA Louisville.

11. Tony Cingrani – SP (9-2, 1.28 ERA, 0.943 WHIP)
After an excellent two months in Bakersfield, Cingrani was promoted to AA and continues to match his impressive performance against tougher competition. Cingrani has a 28/121 BB/K ratio in 98.2 innings pitched this season.

12. Yorman Rodriguez – RF (.226/.251/.360)
The 19-year-old Rodriguez had a rough start in Bakersfield (.381 OPS in 23 games.) The trip to Dayton really seems to have helped so far, as he’s put up a .311/.338/.554 slash line in the 19 games he’s played for the Dragons.

13. Gabriel Rosa 3B/SS (.155/.169/.241)
Rosa is off to a slow start in the first 15 games of Billings season. It’s a rather small sample size to draw any meaningful conclusions, yet.

14. Kyle Lotzkar – SP (7-3, 3.97 ERA, 1.396 WHIP)
Lotzkar had a perfect 3-0 record with a 2.39 ERA in 5 starts for Bakersfield. Since his promotion to AA, he’s been a little more wild (4.8 BB/9), though exhibiting the strikeout rate (11.1 K/9) that he showed prior to the 2011 season.

15. Ryan LaMarre – CF (.273/.360/.367)
The 23-year-old, right-handed centerfielder has improved his walk rate to over 10% of his plate appearances for the first time in his professional career (42 BB in 380 PA) but he’s also seen a slight uptick in his strikeout rate this year (24.5% up from 22.0%).

16. Kyle Waldrop – RF/LF (.270/.337/.394)
This 20-year-old Dayton Dragon is in his 3rd professional season with Cincinnati, having played with the AZL Reds and Billing Mustangs in each of his previous two seasons. Waldrop’s power is down just a little from last year, but his BB/PA rate has improved from 3.4% to 8.1% while his K/AB rate has dropped from 24% to 18%.

17. Amir Garrett – SP (0-1, 15.43 ERA, 2 GS)
Garrett has made just two starts, throwing 2.1 innings as a professional for the AZL Reds.

18. David Vidal – 3B (.260/.326/.437)
Vidal had a .870 OPS after a month at Bakersfield but struggled at first after his promotion to AA Pensacola. Vidal has been improving throughout June and July, and over his past 10 games is hitting .286/.359/.514, matching his production with what he did in the more offensively minded California league.

19. Tucker Barnhart – C (.272/.363/.399)
Tucker continues to get on base frequently and play great defense. Barnhart has thrown out 38% of the 81 attempted base thefts. He was promoted to AA Pensacola last week. Yesterday, Barnhart was named by the Reds as their minor league player of the month after a huge June at Bakersfield (.382/.455/.603 – 1.057 OPS).

20. Juan Duran – LF (.232/.278/.363)
The 20-year-old outfielder has had a rough, streaky first half for Bakersfield, including lows of a .476 OPS in April and highs of batting .300 AVG (.771 OPS) in July.

Former top prospect: Left-handed reliever Donnie Joseph fell off the top 20 radar of many lists after the 2011 season, but he has bounced back in a big way. Splitting his time between AA Pensacola and more recently AAA Louisville, Joseph has a 1.24 ERA, 0.916 WHIP, and a 14/60 BB/K ratio in 43.2 innings.