The San Francisco 49ers drafted Brandon Thomas two years ago, and two seasons have passed without any contributions. The first year was expected, as he suffered a torn ACL during the draft prep process, and was one of Baalke's proverbial "medical redshirts."
Thomas returned to the field in 2015, and got relatively extensive work in the preseason. He played 21, 23, 28, and 34 snaps in each of the four preseason games. Unfortunately, nothing came of that, and he did not play a down the entire season. He was inactive for 15 games, and active but a DNP in Week 5.
It turns out an injury may have played at least some part in the absence. Thomas is over in Australia for his honeymoon, and in chatting with media over there (h/t to mulbring for pointing this out), he said he suffered a high ankle sprain last season. He did not get into any details as to the timing of the injury. In looking back at 49ers injury reports, he was listed in Week 6 and Week 7 with an ankle injury, but that's it.
If that is when the injury happened, this does not provide explanation for his lack of playing time earlier in the year. This is not meant to entirely excuse his lack of playing time, but it's certainly something to at least add to the picture. This coming year is a huge one for Thomas. He is in the third year of a four-year rookie contract. He will be a restricted free agent at the end of the 2017 season, but if he struggles in training camp and the preseason, he very well could be a candidate to be released at the end of camp. My guess is he ends up making the roster, but this summer is a big one for him.
He does seem to recognize that, to some extent. As the article linked above points out, he spent some time working out at the facilities of the Sydney Roosters, even while on his honeymoon. He worked with one of their coaches, Hayden Knowles, and posted some pictures on Instagram.