Let's start with the title of the book...Big hair was all the rage in the mid late '70s; you had the Afros of the (mostly, but by no means all )black players like Garry Maddox, Dick Allen and especially Oscar gamble. Many white players had long hair like Ted Simmons and players of all races sported some sort of fu manchu/ side burn combination. These looks faded in Reagan's conservative '80s, though...the '90s saw first the unfortunate rise in popularity of the mullet, followed closely by the grunge-inspired goatee/van Dyke's, which some players wore well into the 'oos. Now it seems like players will do anything; From Brian Wilson's dyed beard, to Coco Crisp's retro Afro, then braids...then there's the matter of plastic grass....
Back then about half the teams played on AstroTurf, which may have ushered in the "stealing" craze of the era; players like Vince Coleman, Willie Wilson and Omar Moreno, seemingly made a career slapping the ball into the fake turf and beating it out...then making the pitcher's life havoc as they stole almost at will. If these players played most of their games on real grass, they may never have stayed in the majors long (except maybe Wilson, who actually was a good hitter ). Today, with the advent of the olde timey ballpark look, there are only two teams: the Rays and Blue Jays, who still play on AstroTurf.
The uniforms changed; the form fitting, non buttoned jerseys of the '70s and '80s, have given way to a more classic look. One thing I will say that's better today than then; the uniforms aren't nearly as ugly. Bullpen cars are no more. You say this to anyone under the age of 30, and they look at you like you have three heads....relievers used to be carted in by a vehicle that kind of looked like a golf cart with a giant baseball helmet on top of it. I remember one of the first pitchers to refuse to use one, and actually ran in from the bullpen was Al "The mad Hungarian" Hrabosky", who also predates a lot of the "crazier" closers of today, with his wild mound antics and intimidation tactics.
Since the late '70s there have been two strikes; one in '81 and a more catastrophic one in 1994, which killed the season entirely. Oddly, those 2 season marked the two best the now defunct Montreal Expos would have...in 1981, they were and inning away from going to the world series...in '94 they had the best record in baseball, only to see the post season cancelled. The franchise would never see the playoffs as the Expos again. This past season they finally did as the Washington Nationals;having moved there in 2004.
Oh yeah, there's also four new teams: in 1993, the Colorado Rockies and Florida ( now Miami) Marlins and in 1998 the Arizona Diamond backs and Tampa Bay Devil Rays (now just Rays). All four teams have won the pennant, btw, a feat that used to take most expansion teams decades to achieve. I used to marvel at the Kansas City Royals feat of making it to the playoffs after 7 years of existence (or of course, the Mets winning it all after the same amount of time).
And the way we watch the game has changed; it used to be you'd have your local station; mine being WSBK TV in Boston, that would show most (but by no means all) of the games. If you missed it, you'd have to wait until the local news or read it in the Boston Globe the next day. If you wanted to know about other teams (especially National league ones, who you only saw during All Star games and the World series ), you'd have to wait until Saturday, when the show "This week in baseball", narrated by the great Mel Allen, would air. Then you'd see the Dave Parkers and the Andre' Dawsons and the Rickey Henderson's and the Mike Schmidts; players you knew about mostly through your baseball collection. Of course now, there's ESPN, Sports center and more recently "Baseball tonight".