Okay I will try and respond to everyone just based off of what I remember reading.
To whoever mentioned that it helped them to just remember that timing is the first thing to think of and your thumb will follow, I am happy I could help you there. It really has done me wonders.
One little bit to add to that timing thing. Make sure you understand the spray chart of the hitter you are using. If you are trying to power pull pitches with a guy that is not a pull hitter, it won't work as well. If your using a pull hitter, well you won't get much power out of them going the other way (although you can still take advantage of shifts). I was trying to pull/go opposite field a lot with Joc and I struggled mightily with him. Last two games, I have focused on crushing pitches to the allys or to center and have hit two homers with him.
Just keep that stuff in mind. If you read the strategy guide in the pause menu, it does mention that the hitters spray tendencies DO matter.
As to the people that are struggling because they move the PCI too much and pop stuff up a lot, well I am right there with you and recently struggled with the same thing.
I recently got through it though by understanding what I was doing wrong and working to correct it. I do hit more grounders now on low pitches, but that means I am now crushing pitches in the middle of the plate. Also keep in mind that, ground balls have higher BABIPs than fly balls, so grounders are not necessarily a bad thing.
Also, don't try and cover the entire plate at once, ESPECIALLY in a hitters count! That is really key. Look for the pitch you want. This can be done by noticing your opposing pitchers tendencies (this could also include someone online starting each at bat by throwing at the "cold" zones for each batter. I noticed a lot of people do this). Where they throw, the pitch they throw, and it what count. If its 1-0, 1-1, 0-1, 2-1, 3-1, 3-0 just look for a pitch in a certain zone and lay off anything else. There is no need to swing at a pitch you don't want. You might look like an idiot swinging at something offspeed looking for a fastball, but when you do get the fastball, then its boomstick time. For an example of this, watch Nelson Cruz for a couple of games. He looks silly sometimes swinging at a million miles an hour at a breaking ball in the dirt early in the count. Then he protects and uses the whole field to get a base hit with two strikes. There is a reason he's batting like .330 while still also hitting 19 bombs so far.
With that said, USE contact swing with 2 strikes! This is especially useful on inside pitches. I can not even count how many times guys try to throw inside on me with two strikes and since I am trying to protect, I am not necessarily looking only for that pitch. With a contact swing, you most likely won't shatter your bat and will either foul it off, or will get a bloop single. I probably get 1-2 bloop singles per game by doing this. I am by no means a great hitter, but this is one reason I am hitting nearly .330 in 250+ ABs with 77 overall Justin Turner (if your looking for a lead off guy or just a guy to get you lots of hits easily, he's only a bronze and easy to use).
Lastly, keep in mind that in the 2014 MLB season, the Tigers lead the league in team batting average by hitting .277 (The median was .253), so do not get discouraged
.
As for Jack, try playing with your lineup. I actually have struggled with the same problem. I average between 8 and 12 hits per game but I think my runs per game is around 3... that is on the rise though as I have adjusted my lineup and added one more power bat (Flava Fraz!).