One of my pet peeves is when I see players going for flat-out winners at inopportune times. Now, winners come in all shapes and sizes, and it's difficult to encapsulate this concept without some form of live demonstration. Nevertheless, it is important to understand that a smart winner will take place when (1) the opponent can't get to the ball (obviously!!!); and (2) when the risk of missing is small or non-existent. 

Often times, I see a player going for a winner that appears to be aimed directly from the line. If we freeze-frame the positioning of the opponent, we can sometimes see that her location is in the middle of the court. In effect, the ball is 12 feet away from the opponent (i.e., satisfying the first element) but the ball is also 2inches from the line/over the net (coming dangerously close to not satisfying the second component). This is very frustrating for a coach to watch because it's a lot like watching someone go "all in" in a Poker match with a weak hand.

A player has, generally, no business going for winners unless the SECOND element is satisfied. The player will be effective at achieving this objective when the player manages to move the opponent away from the middle of the court. For example, try to move your opponent 2 feet towards the backhand; then, 2 feet towards the forehand side; then 4 feet towards the backhand, then 4 feet towards the backhand side of the court, then maybe 6 feet towards the backhand. At this point, if you go for a winner (the other way) that is 12 feet from the opponent, you are only still aiming 6 feet from the middle of the court (cutting the risk for missing long/wide dramatically). Conversely, if you go for winners when the opponent sits on top of the center-T on the baseline, you HAVE to hit the lines in order for the opponent to not get there. This is HIGH RISK tennis and should be avoided 99% of the plays. 

See website for complete article licensing information.