The story of Big Windup primarily follows the meek and introverted Ren Mihashi, the pitcher for a middle school team that lost virtually every game they played for three straight years. Hated by his previous teammates and completely lacking in confidence, Ren decided that it would be best to give up baseball and start over again at a new school. Much to his chagrin, he finds himself unwittingly added to the roster of the newly-formed Nishiura High baseball team, dragged along in the wake of its force-of-nature female coach, Momoe.
Big Windup is unique among sports anime in that it takes the subject matter seriously and handles it in a relatively realistic fashion. You won't find any pitches that turn into bolts of lightning or seven foot tall super-sluggers taking the plate in this series. What you will find is more strikeouts than hits, innings where zero runs are scored, and hits that are nothing more than fly-balls for an immediate out.
If this makes the series sound boring, I can assure you that it's not. While the cast seems lackluster at a glance, most of the characters themselves actually come across quite well through interactions and emotions that all feel natural. Yes, there is a hotheaded character but he isn't hotheaded enough to be the archetypal idiot you anticipate. Yes, there is also an extremely energetic loudmouth, but he isn't energetic enough to become an obnoxious caricature of a human being and that, right there, is the key to the entire series. At all times, Big Windup appears to know when to draw the line between a character and a caricature.
I'm genuinely hard pressed to find negative things to say about Big Windup. It could use a few more off-the-field episodes and you can't expect a clean ending as the series clearly continues onward into a second season, but that's about the extent of it. The visual style is simple but incredibly well animated, the soundtrack suits the series, the writing is surprisingly good, and I was able to watch 26 dubbed episodes without batting an eye.