Complex sentence: The league peaked at ten teams between 1926 and 1931, however financial pressures led the Pittsburgh Pirates to relocate to become the Philadelphia Quakers in 1930, then to fold in 1931.
Split into simpler sentences: The league peaked at ten teams between 1926 and 1931, however financial pressures led to the demise of several teams. The Pittsburgh Pirates relocated to become the Philadelphia Quakers in 1930 before folding in 1931.