San Francisco is already dealing with a few key injuries at the position and that's created the need for additional depth.
Matt Breida will likely miss the rest of the preseason with a shoulder injury, per Matt Maiocco of NBC Sports Bay Area. Projected starter Jerick McKinnon also injured his knee, although it was described as just a muscle strain, per Adam Schefter of ESPN.
Morris got off to a strong start to his career, piling up 3,962 yards and 28 touchdowns in his first three seasons in Washington. The former sixth-round pick was named to two Pro Bowls in his first three years.
However, Washington drafted Matt Jones in the third round in 2015 in a move that signaled the beginning of the end of Morris' time in the nation's capital. While splitting carries with Jones, he still managed to rush for 751 yards during his final year with Washington.
The 29-year-old opted to move on to the NFC East rival Dallas Cowboys, but that switch may not have turned out the way the veteran had hoped. A month later, the team drafted Ezekiel Elliott with the No. 4 overall pick in the 2016 NFL draft, clearly putting Morris in a backup role.
As a result, his numbers took a major hit, although he was able to show he could still move the football when Elliott had to serve a six-game suspension last year. He ran for 72 yards while his teammate was sidelined, and he averaged 4.8 yards per carry on the season.
At 29, Morris may not be the workhorse he once was. However, he has averaged just 92 carries per season the last two years, which has lead to less wear and tear than some backs of his age. He proved last year he still has something left in the tank and can pick up yards in bunches when called upon.