Complex sentence: Players generally slide feet-first, but sometimes also use a head-first technique, an alternate method used in Major League Baseball at least since the middle-1880s when the innovation was popularized by the St. Louis Browns of the American Association.
Split into simpler sentences: Players generally slide feet-first, but sometimes also use a head-first technique. This alternate method has been used in Major League Baseball at least since the middle-1880s when the innovation was popularized by the St. Louis Browns of the American Association.