You will see this with starter clubs. If you invest in some better clubs as you advance tiers you will see an improvement but still encounter some "deviations" on dinged shots. I play the g10 master set and at least every 4th shot see 4-5 yard deviations on shots that are dinged.
Randomly I will see a huge deviation of about 30-40 yards (usually distance when deviation is that great). The small deviations are built in as a feature of the game but the large ones should be reported by right clicking and submitting bug report to WGT.
Now that said, don't expect any rapid resolution from WGT after submitting bug report. Many players have submitted several hundred bug reports about g10 master 7 and 8 irons deviating way short and the 9 iron deviating incredibly long yet WGT maintains there is nothing wrong with the programming.
It will get better for you so stick with it, but it will also be a source of consistent frustration. Played a round yesterday with the very precise g10 irons and had 6 dinged shots in a row deviate by greater than 5 yards.