Source: http://www.edmontonbridge.ca/Crosby.html
On my convention card under 5 card majors , I have expected length ticked as 4 in 3rd or 4th seat . I do this because I like to preserve the sanctity of lead directors in 3rd seat or to be disciplined by opening my best suit . If that suit is a 4 card major so be it. I am from the Kiz school and I would never open 1
with xxxx in 3rd or 4th seat and 14 HCP’s. I would open a spade (4 cards) or cheat a point and bid 1NT .
When partner is a passed hand her “expected” HCP range from 0-12 . The average hand will be 6 points as a passed hand. This means that the opponents will buy the hand 50 % up to 75 % of the time . Why get partner off to a horrible lead ? In 1st and 2nd seat it is an automatic 1 opener and partner will allow for that with her opening leads . 3 rd & 4th are a different proposition because quite often you just open for a lead.
I loath “testimonials” as rationale to a bidding problem. Bridge logic should prevail. However for those into that : Peter Jones , Stan Cabay , Klimo , Bob Crosby are a few who would never open a diamond in 3rd seat with xxxx . Leads are way too important. Some people seem to have some hang up with 4 card majors. For the first 50 years of Bridge, 4 card majors were the norm.
In Toronto rubber Bridge and in England, 4 card majors are still the norm today. When partner is a passed hand , there is nothing wrong with opening 4 card majors if that’s where your values are. Peter Jones, myself, Stan Cabay have used that tactic successfully for as long as we played the game.
Closed minds are the biggest deterrent to learning and improving in any field …
Opening a diamond in 3rd seat with 
xx 
AKQx xxxx 
Axx is very very wrong. Opening 1 heart has advantages other then just “showing where you live” for lead purposes. Opening 4 card majors are surprisingly preemptive and force the opponents to pass or overcall at the 2 level. Quite often they do not have the requisite shape to enter the auction. There is also a tactical advantage to finding your major suit fit very quickly . Close major suit games are bid and made which are otherwise very difficult to find .
Overcalling 4 card majors for a lead or the best out with a fix hand is quite often good strategy. Playing with BJ , I held AJ10x x AKx AQxxx and there was a diamond opener to my right. I overcalled 1. And BJ leapt to 4. I passed and made +650. We opened up the slip and two pairs played the hand in 2 making 4 ! BJ’s hand Qxxxx Kxxxx x xx so come up with a bid after a 2 overcall !!
Bridge is far more than following rote rules. Rules change depending on the vulnerability and whether you are in 3rd or 4th chair . Partner being a passed hand , necessitates a bidding system that takes that into consideration.