There are three reasons that Steve Lyons gets Unknown Hero status here.
1. His nickname was "Psycho". Lyons was known for his hard-nosed style of play and willingness to get his uniform dirty. In cities like Chicago and Boston, where he spent most of his career, that style of play is incredibly popular. Lyons was also known for his occasional mental lapses, such as the time he accidentally pulled his pants down. At first base. On a nationally-televised game. Admittedly that occurred during his time with the White Sox, but it still counts.
2. His versatility. Lyons was the first super-sub I was aware of. I have always liked these types of players. Jeff Frye and Brock Holt have been a couple of others that I have liked. In his career, Lyons appeared at every position. Yes, even pitcher and catcher. He pitched an inning for the Red Sox in 1991, giving up two hits, but no runs, and even picking up a strikeout. He appeared at every position in 1991 for the Red Sox except catcher. But he did catch an inning in 1993. He initially came up as an outfielder and third-basemen but proved to be very versatile early on. It was this versatility that kept him in the Majors as long as he did.
3. He had four stints with the Red Sox. Lyons came up in 1985 with the Red Sox and played in 133 games after being drafted in the first round by Boston (19th overall) in 1981. Then in late June, 1986, he was traded to the White Sox for future Hall of Famer Tom Seaver. Not many players can say they were traded straight-up for a Hall of Famer. He played the next few seasons with the White Sox before being released in April 1991. He signed with the Red Sox, a decision which he explained by saying "I find that every five years, a man has to change his Sox." He left for the Atlanta Braves in 1992, but was released and picked up by the Expos. He played in 27 games with those two teams before being released again and picked up by the Red Sox, for whom he finished the year. Then in 1993, he again left to join the Cubs. He did not appear in a Major League game for them however, before being released and re-joining the Red Sox once more. I can think of several players who had two stints with Boston. If I thought hard about it, maybe even a player with three stints. But Lyons is the only player I can think of who had four stints with Boston.
You may have noticed I did not discuss Lyons's stats. He was not much of a hitter. His value came almost entirely from his versatility. But there is a reason they are "Unknown Heroes".