Think about it.....a 9' table has 27' of rails and 27.75" of pocket openings (space) while a 7' table only has 21' of rails with 29.5" of pocket openings.............that translates into a 9' table having 8.6% pocket opening area (2 long & 2 short rails) whereas a 7' table furnishes 11.7% pocket opening area of its 4 rails. The pockets on a 7' table, especially the side pockets, are huge in comparison to a standard 9' table. God forbid you use 4.5" pockets like on some Diamond 9' tables I play on. Those pockets can sometimes literally seem demonic like on long cuts, banks & rail shots.
Nonetheless, a 7' table makes a weaker adversary a stronger adversary by way of its larger pockets. Better players play better position which on a 7' table sometimes involves seemingly awful luck such as scratching by accidentally bumping an object ball en route to the desired cue ball position. Or else it's your weaker opponent's God awful slop shots on a 7' table because of its huge pockets. It happens all too often when a better player is matched against a weaker opponent on a 7' table. And you don't always play with 2.25" object balls or cue ball and even the weights vary like crazy too. I mean when was the last time you played with a set of Centennials on a bar table. Regardless, the point is it's easier to park a car in a bigger garage and the same applies to pocketing balls on a 7' table versus a 9' table.
Personally speaking, it's too frustrating playing lesser opponents on a 7' table which only helps them play better. And please no advice about bearing down, focus, and concentrate more, or use more center ball & stop shots etc. on a 7' table......Come on......do the math.......the total pocket opening space on a 7' table is 36% more than on a 9' table (8.6% vs 11.7%). That means the missed cut, rail or bank shots your weaker player experiences on a 9' table tend to drop a lot more often on a 7' table. The better player also enjoys the advantage of the bigger pockets but better players also get hurt more often on a run out because of accidental bumps & scratches. Sure that's the rub of the green for every player....right? Remember that weaker opponents seldom run the table and have not mastered cue ball position other than playing the table shot to shot or perhaps 1 or 2 shots ahead at best. So the weaker opponent misses shots more often and their scratches tend to be a lot less accidental and more from poor shot making skills. The better player has the ability to run a table and in the process, more bad luck things seem to happen on a 7' vs.9' table.
Play your weaker opponent a 10 ball match on a 9' table and the stronger player should dominate since there's no luck or slop involved. The called pocket requirement of 10 ball just makes even more difficult for a weaker opponent to beat a more skilled, better opponent, especially on a 9' table. That's just the facts of life in a pool room. I stopped playing APA because it's played on what I refer to as the "sandbox". Gone are the days where men battled it out on a 10' table. Now that's the way pool was intended to be played and the 9' table was only introduced by Brunswick back in the early 60's to promote increased home recreational play. The 9' table subsequently replaced the 10' table as the standard for championship play (US Open). Now only 3 cushion is played on a 10' table and of course, American Snooker.