Statistical investigations of the transmission performance of Adaptively Modulated Optical Orthogonal Frequency Division Multiplexing (AMOOFDM) are undertaken in single-channel, optical amplifier-free, Multimode Fiber (MMF)-based links using Intensity Modulation and Direct Detection (IMDD). Numerical simulations are performed using statistically constructed 1000 worst-case MMF links having 3-dB bandwidths varying in a range of 220-490 MHz middot km. It is shown that, by employing practically available devices, >30 Gb/s over 300-m AMOOFDM signal transmission is achievable in 99.5% of already installed MMF links, while by employing components that may be available in the future, the AMOOFDM technique is capable of supporting 100 Gb/s over 150-m signal transmission in 99.5% of already installed MMF links. In addition, it is confirmed, from a statistical point of view, that AMOOFDM has excellent flexibility and great robustness to different types of fibers and lasers, restricted launch conditions and practical implementation-related factors such as optical connector offset. It is also found that cyclic prefix and quantization are the key factors limiting the maximum achievable transmission performance of the AMOOFDM technique.