Poston, one of a dozen remaining players recruited to CU by former coach Dan Hawkins, played in nine games on defense for a total of 162 snaps last season, making 11 total tackles.
MacIntyre said Poston, a psychology major, has one class remaining to take in June before earning his degree and moving on to pursue a master's degree.
CU added defensive lineman Leo Jackson as a late signee in the 2014 recruiting class during spring break.
MacIntyre said he liked Jackson in the evaluation process, including his size, 6-foot-3, 275 pounds. He said the team needs more defensive lineman and knowing so many junior college coaches allowed CU coaches to find one who could help them and would qualify academically.
"He's real athletic, real bright and we're excited," MacIntyre said.
Jackson is a product of Atlanta. He missed a year of football in 2012 when he was not offered a scholarship by a major program out of high school. He played at Foothills College in Northern California last fall recording 24 tackles in eight games. MacIntyre said he likes adding junior college players who have four years to play three, which is the case with Jackson, who will be a 20-year-old sophomore.
Senior safety Terrel Smith returned to practice Monday and made an interception that caught MacIntyre's eye. Smith redshirted last season with a shoulder injury and missed much of the first portion of spring with a leg injury. ... Running backs Christian Powell and Michael Adkins were back on the field after missing all or part of the first part of spring with injuries.