ROI stands for return on investment. In betting, it means the player efficiency and results. When assessing the bettor's professionalism, it is important to consider not only his or her ROI, but also the total number of bets. A reliable indicator is obtained when considering figures from 100, preferably from 500.
Rushing about is the style of making bets, typical for novice bettors who do not analyse the situation. Off-the-cuff means making a bet without studying the forecast first, at random.