The game of Go is a board game with a long history that is much more complex than chess. The uncertainties of this game will be higher when the board size gets bigger. For evaluating the human performance on Go games, one human could be advanced to a higher rank based on the number of winning games via a formal human against human competition. However, a human Go player's performance could be influenced by factors such as the on-the-spot environment, as well as physical and mental situations of the day, which causes difficulty and uncertainty in certificating the human's rank. Thanks to a sample of one player's games, evaluating his/her strength by classical models such as the Bradley-Terry model is possible. However, due to inhomogeneous game conditions and limited access to archives of games, such estimates can be imprecise. In addition, classical rankings (1 Dan, 2 Dan, ...) are integers, which lead to a rather imprecise estimate of the opponent's strengths. Therefore, we propose to use a sample of games played against a computer to estimate the human's strength. In order to increase the precision, the strength of the computer is adapted from one move to the next by increasing or decreasing the computational power based on the current situation and the result of games. The human can decide some specific conditions, such as komi and board size. In this paper, we use type-2 fuzzy sets (T2FSs) with parameters optimized by a genetic algorithm for estimating the rank in a stable manner, independently of board size. More precisely, an adaptive Monte Carlo tree search (MCTS) estimates the number of simulations, corresponding to the strength of its opponents. Next, the T2FS-based adaptive linguistic assessment system infers the human performance and presents the results using the linguistic description. The experimental results show that the proposed approach is feasible for application to the adaptive linguistic assessment on a human Go player's performance.