Not a lot of golfers think when they are playing golf. They get use to hitting balls on the range where it is flat and mown tight. In playing lessons I see it often when putting students in a situation to see what they do and that is sometimes nothing different. They grab their normal club they would hit on the range and do not think about this. Let’s take a look at the results of the above lies using TrackMan where all the balls came out of the center of the club face. This writeup is covering the YouTube Video: Perfect Lie vs. Different Rough Lies
The above numbers were from the flat lie. There was no grass between the club face strike and the ball. The club was an 8i and first ball of the day after setting up all the filming equipment and TrackMan.
The above image is a comparison of the first ball with the clean strike and one of the middle two balls. Not going to put up both of the middle ball numbers because they were similar. If you take a look at the first image above with the lies although the balls look different there is minimal grass/debris between club face and ball strike. The grass is an overseeded rye in Arizona where the blades are thin and easy to get though but still get in the way of contact. Club speed was a mile an hour slower but with the grass interference the ball speed dropped 9mph (2-3 of those due to swing speed) but the carry was 6 yards longer. Why is the question? If you look at the launch angle it was almost 2* higher but the spin was 2469. This is like launching a driver off a tee. For optimal driver launch at that club speed and spin rate it would be around 17* and carry 197 yards or so. This is known as a flyer lie where the ball travels longer than expected.
Now let’s look at the bottom ball where it was sitting 1/2 way down in the rough. Did not have a thick piece of grass to drop the ball in but the deeper down in the grass the more the numbers will change for the worse. Think of grass like having pillows stacked out in front of your stomach and someone was about to deliver a blow. The more you have the less you would feel the strike. Same thing happens between the club and ball delivery which is known as the smash factor. That is the ball speed decided by club speed. The swing speeds were the same but the energy transfer dropped by .14 smash lowering the ball speed from 115.7 to 103.7. Now the ball speed is starting to come out slower with more cushion between the strike and the carry distance is starting to go down. Launch angle went up higher but at some point there will be too much grass to get through if the lie was thicker and deeper where the ball might not get airborne.
There is just a few examples of how grass starts to interfere with the flight. The more junk in the way the more unpredictable the ball flight and outcome can become. When it starts to get extreme the goal is to get the ball back to play where you can control the golf ball. Do not move it to another bad lie but take your lump and keep going forward. Start paying attention to your lies when you are out playing. The more you play and start recalling what lies looked like while recalling past memories of what happened in similar situations the more you will understand what the ball might do. This gives you either a green proceed like normal light, yellow cautious light, or red stop get back to play sign.