The contrasts between Cardinals outfielders Jon Jay and Colby Rasmus are endless and fascinating.

Experts projected Jay as a reliable No. 4 outfielder and Rasmus as a potential “five-tool” standout in center field.

Jay has become the model of consistency. He hit .301 in his minor league career and entered the weekend with a .301 career big league average. Although he tailed off after a torrid start last season, Jay has suffered no such slippage this season.

Rasmus has put up big numbers in spurts – although these spurts have become far less frequent.

Jay played for a big-time college baseball program, the University of Miami and logged 672 at bats for the Hurricanes. He piled up All-America and all-conference honors. He came to the Cardinals organization as a polished player ready to produce.

Rasmus played for his father at Russell County High School in Alabama before signing with the Cardinals. He arrived as a raw, high-upside talent looking to grow into the outsized expectations scouts had for him.

Jay has played in a few more minor league games, 1,564 to 1,553. He is slightly older; Jay turned 26 years old in March and Rasmus turns 25 in August.

But while Jay has absorbed instruction and become more adept at making adjustments at the plate, Rasmus has proven slump-prone and difficult to coach.

Jay blended easily with veteran teammates upon his arrival while Rasmus did not.

Jay has fulfilled his offensive potential at the big league level and Rasmus has not.

Neither player has defined their career to this point, but Jay has outplayed Rasmus considerably during the 2011 season.

The weekend series in Cincinnati underscored this. Jay had a three-hit game Saturday and drew a walk in a critical pinch-hitting appearance Sunday. He pushed his season average to .310.

Rasmus went 0 for 7 with a couple of walks and a run scored, continuing a months-long offensive slide. His season average plunged to .241.

Now that the Cardinals are closer to full strength, manager Tony La Russa can lean on his best (or hottest) players while filling out his lineup card.

Rasmus is no longer the everyday center fielder by default. He will have to earn his at bats and Jay will provide worthy competition.

Will Rasmus accept the challenge and finally break out his funk? Or will his perplexing downturn continue?

Might his best option be a return to Triple-A Memphis to get a bunch of at bats away from this pressure cooker? My colleague Bernie Miklasz makes just that case.

Until recently, outsiders wondered if Jay could be a valuable trade chip as the Cards look to shuffle their assets and fill some glaring holes.

Now Rasmus is front and center in the trade speculation. Last season Colby suggested a trade might be best and his father seconded that notion this season.

There has been no such chatter from the Jay camp. Jon has blended nicely into this team’s much-improved chemistry. It seems like he is always smiling.

Cards fans will watch the next the coming weeks with great interest. Will Rasmus pull himself together, mature as a ballplayer and deliver during the stretch run?

Or will Jay have to step in to provide the offense and energy this batting order needs in the No. 2 hole ahead of Albert Pujols?

In this tale of two outfielders, the next few chapters could be quite dramatic.