Saunders Analysis, May 23rd, 2018
First taking a look at the spray charts on batted balls from 2016 and 2017 although sample size is different, one thing that is of particular interest is the amount of fly balls to left field and ground balls concentrated to the pull side. Anytime that we see a pattern like this, the first thing that comes to mind is barrel path in that the bat is "cutting" across the zone. You see the barrel working almost to contact still on the downswing and then cutting across the zone only beginning to work upward towards the pull side. While this is natural in regards to swing plane, when a player is hitting line drives (and most hard contact) to the pull side (with a lot of ground balls) and weak contact to the opposite field, this tends to be the place to begin. In 2016, while the sample size is greater, there is much more consistency through the middle of the field.
Looking at the comparative swings from 2016 (Blue Jays) and 2018 (ST-Royals) the one area that jumps out is the lack of tension being created through the rear (left) forearm . The initial move, while it seems to be more about creating rhythm and timing, in 2016 seemed to produce more torque through the top hand. You can see that as he loads, the rear elbow begins to tilt as the barrel tilts (2016) where in comparison in 2018, the hands are tilting with little connection through the forearm. This move is highly important as you can see that it "connects" better through the rear arm, shoulder, scap, all very important pieces to the swing sequence.
Being a LHH and RH-throwing guy, a lack of torque in the top hand leads to the body wanting to get the hands out away from the body to produce force. This "tension hunting" is directly related to the top hand and how he controls/feels the barrel through his load. If there is not enough tension in that spot to get the bat working around the hands, the center of the swing will drift forward as the front side "pulls" to create tension.
You can see on some of the videos where he has to "rush" forward and over-commit as it appears his body is searching to create tension in time to see the ball (See video below).
I would highly recommend focusing on continuing to create tension with the initial movement. Focus on the top hand connecting through the barrel so that the tension builds in the forearm. This will help limit the body's response to want to speed up the hands or "pull" the hands with the lead arm. A concept that a lot of hitters relate to is the feeling of loading down with the lead elbow to the ground rather than the hands drifting back or away from the center of the hitters body. This allows for the body to compress (like a coiled spring) and release more effectively.