For the most part I think the rosters are pretty solid, but it is always fun to play "what if." If someone gave me the power to change the rosters, here are some changes I'd make to make the game more interesting to me. Your mileage may vary. The way I have this set up, every team is still represented, although it violates the real-life rule that no organization can have more than two players on the rosters.
UNITED STATES ROSTER
Tyler Glasnow, RHP, Pittsburgh Pirates: In the midst of a breakout season, Glasnow is only 19 but has a 2.48 ERA with a 110/43 K/BB in 76 innings for Low-A West Virginia in the Sally League. He's holding hitters to a mere .153 average, he can hit the mid-90s, and his secondary pitches are coming around. He was a fifth round pick in 2011. I would put him on the roster instead of C.J. Riefenhauser.
Kevin Plawecki, C, New York Mets: This 2012 supplemental first round pick out of Purdue is hitting .324/.393/.494 this year in A-ball and is also a skilled defender. I would put him on the roster in place of James McCann. Plawecki's presence will also placate hometown Mets fans who might be angry at me for taking Brandon Nimmo off the squad (see below).
Tyrone Taylor, OF, Milwaukee Brewers; A second round pick in 2012, Taylor is having a really good season in the Midwest League (.301.368/.462, 15 steals) and has the tools and athleticism to continue this at higher levels. He's younger and has a considerably better track record at this point than the more famous Nimmo, who he'll replace on the roster for me.
***I had originally planned to kick C.J. Cron off the list in favor of Garin Cecchini, but when Joey Gallo got hurt, Cecchini was placed on the real roster. I thought about removing Billy Hamilton but decided to leave him on; his speed is just really fun to watch.
The need to have as many countries represented as possible limits what you can realistically do with the World roster, but there are still some adjustments I'd make to enhance that could interest.
James Paxton, LHP, Seattle Mariners: Although he's having an erratic year in Triple-A (4.63 ERA, 91/39 K/BB in 91 innings), this is still a guy who is close to the majors. I'd put him on the pitching roster in place of Carlos Contreras. Paxton also fills in the "Canadian slot" for Jordan Lennerton, who at age 27 is hard to consider a genuine prospect.
Kennys Vargas, 1B, Minnesota Twins: The ranks of first base prospects are actually pretty thin right now, but an interesting one is Vargas, fairly young at age 22 and crushing the ball in the Florida State League (.300/.372/.530). He's a switch-hitter with outstanding power but could be a born DH. He was signed as an undrafted free agent from Puerto Rico in 2009.
Julio Morban, OF, Seattle Mariners: Age 21, from the Dominican, hitting .297/.359/.461 in Double-A. I would put him on the roster ahead of Yeison Asencio, another Dominican who is having a solid year and has some tools himself but is almost three years older.
Danry Vasquez, OF, Detroit Tigers: He's only 19 but is hitting .292/.345/.397 in the Midwest League, plus having a Tiger to replace Lennerton is a nice idea. I would put Vasquez on the roster in place of fellow Venezuelan Jesus Galindo, who is quite fast but has no power and is three years older than Vasquez, playing at the same level.
What changes would you make?