But through two games of the 2007 campaign, the A's are still trying to get every facet of their team working in unison.
On Tuesday night at Safeco Field, Geren's trusty relief corps fired a dud in an 8-4 loss to the Seattle Mariners.
The A's have gotten decent starting efforts from Dan Haren and Joe Blanton in their first two games.
In Monday's season opener, the A's bats were nowhere to be found. A day later, the A's showed some spunk at the plate, only to see a breakdown in another area.
The visitors erased a three-run deficit to tie the game 4-4 in the top of the seventh. Geren summoned Kiko Calero to replace Blanton to start the bottom of the seventh.
Calero, who led the team with 70 appearances in 2006, quickly found trouble. Jose Guillen led off with a single, and two batters later Yunieski Betancourt deposited a 2-0 pitch over the left-field fence for a two-run homer that pushed Seattle ahead 6-4 and sent the crowd of 25,287 into a frenzy.
Calero allowed a single to Jose Lopez before stepping aside for fellow right-hander Justin Duchscherer to face Ichiro Suzuki. Duchscherer came in having struck out Suzuki 12 times in 23 career at-bats, more than any other pitcher.
But this time, Suzuki drilled a triple to the right-center field gap that scored Lopez.
A sacrifice fly by Adrian Beltre padded Seattle's lead to 8-4. That allowed the Mariners to breathe a little easier, and manager Mike Hargrove let ex-Cal star Brandon Morrow close things out in the ninth inning for his major league debut.
After dropping 17 of 19 games to the A's last season, the Mariners have opened the season with two straight victories over the defending American League West champs.
The A's took an early 1-0 lead on Mark Ellis' sacrifice fly in the second inning.
But Richie Sexson's bat that got the Mariners' offense rolling again. Blanton caught too much of the plate with a full-count pitch in the second inning and the lanky slugger drilled it the opposite way for a two-run homer that put Seattle ahead 2-1.
It was the second home run for Sexson in as many days.
The Mariners padded their lead in the fifth inning. Guillen led off with a double, and then Kenji Johjima hit a low liner to right field that the sliding Bobby Kielty could not make a play on. The ball ricocheted about 30 yards away from him, allowing Guillen to score easily.
Johjima got caught in a rundown between second and third bases when the next batter, Betancourt, hit a comebacker to Blanton. The A's ran down Johjima for the out, but not before Betancourt made it to second. That would prove costly for the A's, as Betancourt scored on a two-out single by Suzuki to make it 4-1 Seattle.
How they scored
Athletics second: With one out Kielty walked. Crosby singled, Kielty to third. Ellis hit a sacrifice fly, Kielty scored. Athletics 1, Mariners 0.
Mariners second: Ibanez infield single. Sexson homered, Ibanez scored. Mariners 2, Athletics 1.
Mariners fifth: Guillen doubled. Johjima doubled, Guillen scored. Betancourt grounded into fielder's choice, Johjima caught in rundown between second and third, Betancourt to second. Lopez popped out. Suzuki singled, Betancourt scored. Mariners 4, Athletics 1.
Athletics sixth: With one out, Bradley homered. Mariners 4, Athletics 2.
Athletics seventh: Mateo pitching. Swisher singled. Kielty grounded out, Swisher to second. Crosby flied out. Ellis singled, Swisher scored. Kendall doubled, Ellis scored. Mariners 4, Athletics 4.
Mariners seventh: Calero pitching. Guillen infield single. Johjima popped out. Betancourt homered, Guillen scored. Lopez singled. Duchscherer pitching. Suzuki tripled, Lopez scored. Beltre hit a sacrifice fly, Suzuki scored. Mariners 8, Athletics 4.