A Cardinal rule of "Playing Football" states that St. Louis boasts the finest pass protection in the NFL.

Statistics of recent seasons bear out this observation more often than not. Statistics can be misleading, however. A few other front fives may appear to afford their quarterback as much time and safety as the Cards' Jim Hart enjoys, but they do so under quite different circumstances.

New England, for instance keeps a defensive rush honest in large part because of the fear its running game generates. Ken Stabler has a security blanket behind Oakland's offensive blocking, for the run of Upshaw and Shell. Bert Jones' mobility makes the Baltimore pass protection look better than it usually is.

There are better offensive lines in the NFL than the Cardinals, on balance when blocking for running backs and protecting the passer are equal considerations. But taken separately, in terms of pass blocking only no other combination can complete with Dierdorf, Dobler, Banks, Young and Finnie.

They do it largely on their own, without a back being kept in for extra help in picking up a blitzing linebacker or safety. Hart is free to flood the passing lanes with receivers. Only rarely does one of these five linemen break down, as Finnie did a few weeks ago against Dallas' Harvey Martin. That was no crime. Martin is now the best pass rusher in professional football.

St. Louis according, lives or dies with the pass.Hart was 17 for 24 last Sunday in the Cardinals' 49-31 thumping of the New Orleans Saints. Equally important, he handed off to Terry Metcalf 17 times, for 78 yards and Wayne Morris ran for 95 yards and four touchdowns. Metcalf no long plays on third down only.

Now, if only the St. Louis defense does not fall asleep as it so often does, the Cards are an excellent mythical bet Monday night at home against the New York Giants. They are favored by 11 points. I'll take a little plunge, for $250. Secure in the knowledge that Don Coryell's club can score 35 points, if it has to against the Glants.

New York's strength is its defensive line and line-backing. Matching strength against strength is the way to approach "Playing Football" when the matchup isn't really even.

In other words St. Louis offensive line will again provide Hart with plenty of time. The Giant corner-backs will be exposed as inadequate. I doubt New York will generate much offense, even against the Cardinals. The big danger is St. Louis jumping out to a 21- or 28-point lead too quickly, then relaxing and winning the game but not by 11. The Cards led the Saints 21-0, in the second quarter last week. At halftime , the score was 21-21.

St. Louis, the Giants and Washington all are 3-3 and very mich in the running for the NFC's wild-card spot. The Cardinals get there.

The Head Linesman makes Oakland a four-point favorite over the Broncos in Denver Sunday altough, two weeks ago, Denver blew out the Raiders in Oakland, 30-7. Oakland had 21 first downs that day to Denver's eight but Stabler was intercepted seven times. Unbelievable.

Everything says Denver can't beat Oakland again - except emotionally right now, the Broncos are eligible to achieve anything. Stay clear of this game. The same advice applies to Pittsburgh-Baltimore, where all signs point to a Steeler victory. That could be a trap.

For the record, I'll tip-toe through Washington giving 5 (up from 4) over Philadelphia. Buffalo giving Seattle 4, Green Bay getting 4 from Chicago. Detroit getting 14 from Dallas, Houston getting 7 from Cincinnati, Cleveland giving Kansas City 10. New Orleans getting 8 from Los Angeles. Atlanta getting 5 (down from 5 1/2) from Minnesota, the New York Jets getting 13 1/2 from New England. Denver getting 4 from Oakland, Pittsburgh getting 1 (up from even) from Baltimore, San Diego getting 6 from Miami and San Francisco giving Tampa Bay 15.