| Ryan Castellani | P | Minors | N | 6-4 |
195 |
R-R |
1996-04-01 |
22.171 | Phoenix,Arizona |
 | AA | 2014-2018 | - | 2014- 2- 48-COL | 2018-08-23 | Activated from disabled list | 2016-04-07 |
| Frank Duncan | P | Minors | N | 6-4 |
200 |
R-R |
1992-01-30 |
26.233 | San Diego,California |
| AAA | 2011-2018 | - | 2014-13- 401-PIT | 2018-06-15 | Assigned to Hartford (AA) | 2018-03-26 |
| Parker French | P | Minors | N | 6-2 |
225 |
R-R |
1993-03-19 |
25.184 | Melbourne,Australia |
 | AA | 2012-2018 | - | 2015- 5- 137-COL | 2018-09-01 | Activated from disabled list | 2016-05-05 |
| Rico Garcia | P | Restricted | N | 5-11 |
190 |
R-R |
1994-01-10 |
24.252 | Honolulu,Hawaii |
| AA | 2013-2018 | - | 2016-30- 890-COL | 2018-09-01 | Placed on temporarily inactive list | 2017-07-28 |
| Rayan Gonzalez | P | DL-60 | N | 6-3 |
175 |
R-R |
1990-10-18 |
27.336 | Arecibo,Puerto Rico |
 | AAA | 2009-2018 | - | 2012-21- 648-COL | 2018-05-22 | Assigned to Hartford (AA) for rehab | 2018-05-11 |
| Sam Hilliard | P | Minors | N | 6-5 |
225 |
L-L |
1994-02-21 |
24.210 | Arlington,Texas |
| AA | 2013-2018 | - | 2015-15- 437-COL | 2018-06-02 | Activated from disabled list | 2017-04-06 |
| Marc Magliaro | P | Minors | N | 5-11 |
175 |
R-R |
1990-02-17 |
28.214 | monroe,New Jersey |
| AA | 2013-2018 | - | | 2018-08-26 | Activated from disabled list | 2017-04-19 |
| Brian Moran | P | Minors | N | 6-3 |
188 |
L-L |
1988-09-30 |
29.354 | Rye,New York |
| AAA | 2007-2018 | - | 2009- 7- 203-SEA | 2018-07-18 | Assigned to Hartford (AA) | 2018-07-14 |
| Sean Nolin | P | Minors | N | 6-4 |
235 |
L-L |
1989-12-26 |
28.267 | Seaford,New York |
| MLB | 2010-2018 | 2013-2015 | 2010- 6- 186-TOR | 2018-05-22 | Assigned to Hartford (AA) | 2018-02-27 |
| Craig Schlitter | P | Minors | N | 6-0 |
190 |
R-R |
1992-05-16 |
26.126 | Guilford,Connecticut |
| AAA | 2011-2018 | - | 2014-27- 803-COL | 2018-08-15 | Activated from disabled list | 2018-06-27 |
| Jesus Tinoco | P | Minors | Y | 6-4 |
190 |
R-R |
1995-04-30 |
23.142 | San Antonio de Maturin,Venezuela |
 | AA | 2012-2018 | - | | 2018-03-10 | Assigned to Hartford (AA) | 2017-11-20 |
| Jack Wynkoop | P | DL-7 | N | 6-5 |
185 |
L-L |
1993-11-02 |
24.321 | Virginia Beach,Virginia |
| AA | 2013-2018 | - | 2015- 6- 167-COL | 2018-07-12 | DL-7 Injured | 2016-06-23 |
| Robbie Perkins | C | Minors | N | 6-0 |
175 |
R-R |
1994-05-29 |
24.113 | Canberra,Australia |
| AAA | 2013-2018 | - | | 2018-09-01 | Reinstated to active roster | 2018-08-24 |
| Sam Tidaback | C | Minors | N | 6-0 |
190 |
R-R |
1993-10-06 |
24.348 | Berwyn,Illinois |
| AA | 2013-2018 | - | 2016-21- 644-CHN | 2018-08-27 | Reinstated to active roster | 2017-06-22 |
| Brandon Bednar | 2B-SS | Minors | N | 6-4 |
170 |
R-R |
1992-03-21 |
26.182 | Stuart,Florida |
| AA | 2011-2018 | - | 2013- 7- 222-SFN | 2018-06-21 | Assigned to Hartford (AA) | 2018-06-21 |
| Scotty Burcham | IF | Minors | N | 5-11 |
165 |
R-R |
1993-06-17 |
25.094 | Palm Desert,California |
| AA | 2012-2018 | - | 2015-25- 737-COL | 2018-07-26 | Activated from disabled list | 2017-04-06 |
| Josh Fuentes | 3B | Minors | N | 6-2 |
215 |
R-R |
1993-12-19 |
24.274 | Trabuco Hills,California |
| AAA | 2013-2018 | - | | 2017-09-01 | Reinstated to active roster | 2016-05-26 |
| Reid Humphreys | SS | | N | 6-1 |
201 |
R-R |
1994-11-21 |
23.302 | Brandon,Mississippi |
| AA | 2014-2018 | - | 2016- 7- 200-COL | 2018-08-21 | | 2018-06-07 |
| Ryan Metzler | IF | Restricted | N | 6-1 |
170 |
R-R |
1993-03-20 |
25.183 | Glen Burnie,Maryland |
| AAA | 2012-2018 | - | 2014- 9- 264-TOR | 2018-09-01 | Placed on temporarily inactive list | 2018-06-03 |
| Nelson Molina | SS-2B | Minors | N | 6-3 |
175 |
L-R |
1995-04-30 |
23.142 | Arecibo,Puerto Rico |
| AA | 2013-2018 | - | 2013-11- 320-MIN | 2018-07-21 | Activated from disabled list | 2018-05-13 |
| Brian Mundell | 1b | Minors | N | 6-3 |
225 |
R-R |
1994-02-28 |
24.203 | Santa Clarita,California |
| AA | 2013-2018 | - | 2015- 7- 197-COL | 2017-10-04 | Activated from disabled list | 2017-04-06 |
| Dom Nunez | 3B | Minors | N | 6-0 |
170 |
L-R |
1995-01-17 |
23.245 | Elk Grove,California |
| AA | 2013-2018 | - | 2013- 6- 169-COL | 2017-04-06 | Assigned to Hartford (AA) | 2016-04-07 |
| Matt Pierpont | IF-P | Minors | N | 6-2 |
202 |
R-R |
1991-01-25 |
27.237 | Canonsburg,Pennsylvania |
| AA | 2010-2018 | - | 2013-26- 769-COL | 2017-05-04 | Assigned to Hartford (AA) | 2017-04-10 |
| Roberto Ramos | 1B | Minors | N | 6-4 |
220 |
L-R |
1994-12-28 |
23.265 | Hermosillo,Mexico |
 | AA | 2014-2018 | - | 2014-16- 473-COL | 2018-06-21 | Assigned to Hartford (AA) | 2017-04-06 |
| Omar Carrizales | OF | Minors | N | 6-0 |
175 |
L-L |
1995-01-30 |
23.232 | Maracay,Venezuela |
| AA | 2013-2018 | - | 2012- UDFA-COL | 2018-06-22 | Activated from disabled list | 2016-04-07 |
| Yonathan Daza | OF | DL-60 | N | 6-2 |
190 |
R-R |
1994-02-28 |
24.203 | Maracay,Venezuela |
| AA | 2011-2018 | - | | 2018-09-04 | DL-60 Left shoulder strain | 2017-11-20 |
