In addition to what Plaman has said, the tackling issue is possibly due to your positioning. High closing down can leave players out of position, causing them to make more last ditch challenges which can reduce the % of completed tackles.
Do you play standard all the time, or do you change your strategy to suit the match and the opposition? This may cause you problems in breaking down smaller sides (control or attack may be more preferable), and one ahead you might want to try being a little more cautious (standard, counter or even defend, depending on the situation).
As Plaman says, though, what types of goals are you conceding? Look at both how the actual shot goes in but also how the build up could have been avoided.