Every time you play a certain shot from a certain position you build a credit for its opposite. A key area for such credits is back left. Every time you play a straight drop from there you create a credit for the cross-court drive (or lob) - into the opposite corner.
So, in amongst immaculate straight drives from back left, you should play reasonably frequent straight drops (safe attack - good risk/reward). Fairly quickly, the opponent will be forced to cover - and lean towards - front left/back left. This opens up back right. Played too soon - or too obviously - the cross-court to back right will be easily intercepted and dealt with but, with the correct straight groundwork (which is also safe), the cross-court will pass your opponent and do real damage.
Having played the cross-court, you have of course created credits for front left (and back left). The opponent now obviously has to cover the cross-court slightly more, enabling your drops/drives to do more damage again. This leads to him having to cover them slightly more etc etc.
If you never play the drop (or boast or lob or reverse angle etc), the game will obviously continue but your drives will be less effective even if they are hit exactly the same as the player who does also plays drops - because there is less doubt created. The opponent does not have to lean slightly more forward to cover the short balls, so the deeper ones are easier. You are a hacker. If you overplay the drops etc - or play them too obviously - they will be dealt with easily. You had better be fit.
Robert Forde