Aguirre had always been envious when he'd hear the tales Bob Costas and Billy Crystal shared about the role baseball played in their upbringing. About all those instances when they'd sit in the stands alongside their fathers. How they'd watch. And, more important, how they'd bond.
Baseball had been a part of Aguirre's upbringing, too, but not in that way. His father had not been around, leaving his mother to raise seven children mostly alone.
When Jackson was born, Aguirre vowed he'd be there for his children. And he vowed that baseball would be, too.
The tradition began with his son and soon came to include daughter Alanna, now 5. Born to a father who through 2011 hadn't missed a D-backs Opening Day or final home game (regular season or playoff), the Aguirre children have grown up at Chase Field. Neither had missed a home opener, either.
That changed in April.
The excitement of joining their dad at the ballpark had, for months, been replaced by the anticipation of seeing him check in on Skype. Stationed in Kandahar, Afghanistan, Lt. Col. Paul Aguirre discovered changed priorities, topped by the Thursday video chats he'd have with his kids.
Aguirre had come to expect an array of questions from Alanna, the more inquisitive of the two. With Jackson, time was regularly spent on spelling homework.
Aguirre signed off last Thursday after promising his children he'd be home soon. He never did say when, promising only that he'd be delivering a special message when Alanna and Jackson attended Monday's D-backs' game.
The children were excited, even though they knew the message would be transmitted via video, as all of dad's greetings had been since October. At least, that is what they had been led to believe.
"Dad is going to be up there," Jackson said on Monday evening, pointing to the Chase Field video board. He and his sister were standing along the dirt backstop, patiently waiting to be ushered onto the field. Each wore a D-backs shirt and had a baseball in hand, oblivious to the attention of all the nearby camera crews.
The kids had been repeatedly reminded of the script: Their dad would be sending a video message from Afghanistan, which they would watch on the JumboTron. Then, because they had been so good during their father's seven-month deployment, the D-backs would invite them to throw a ceremonial first pitch.
When the public-address announcer identified the family, Jackson and Alanna, accompanied by their grandmother and an uncle, began walking to the mound. Aguirre slowly climbed the steps adjacent to the D-backs' dugout. He admitted afterward that at the moment he spotted his children, it was harder to keep back the tears than it ever was keeping the secret.
Aguirre, a 22-year member of the U.S. Armed Forces, had felt compelled to serve overseas since 9/11. He had done plenty of work internationally during his time in the Army, but never on official deployment. When he moved into the Air Force branch, he again found himself working only in domestic positions.
That changed for the native of Phoenix a little more than two years ago, when his supervisor told him that after a certain 18-month inspection was completed at the Sky Harbor Air National Guard Base, he would be free to volunteer for deployment.
Aguirre never hesitated.
"It was something where I really wanted to do my part," he said. "I had been around a lot of soldiers that have gone overseas. I've seen the hardships of families. I had worked very closely with some families of soldiers who were killed in action. I've seen the sacrifices. I've seen what they have had to go through. I know I was doing my bit here, contributing the way I was supposed to be contributing, but by the same token, I felt like I needed to go overseas and do my part as well."
Aguirre's time in Afghanistan was split among a variety of projects, many of which were designed to help the Afghan people become self-sufficient. Living in an area where less than 10 percent of the population is literate and where clean water is a rarity, Aguirre led efforts to fix both.
He helped initiate drives to collect school supplies, and he facilitated meetings with village elders to teach them about various government processes. One of his most ambitious endeavors was to assist with the implementation of approximately 100 water-purification systems.
By the time he left, not only did some villages have adequate drinking water, police and village elders had been schooled on how to keep the systems working. For a people that had been regularly burying infants who'd died from drinking contaminated water, it was, literally, life-saving work.
"A lot of the families there were spending what little money that they have just on medicine and doctor bills for their kids just because of how tainted the water was there," Aguirre said. "That was a very satisfying, very gratifying mission to do."
His desire to serve hasn't waned, it's only that the desire to father his children pulled him home. Had he not had kids, he said, he would have undoubtedly remained in the Middle East.
This surprise had been in the works for a few weeks, prompted by an email Aguirre sent the D-backs. Appreciating baseball's place in his relationship with his children, he felt no better setting for a reunion. The D-backs immediately jumped into the planning process.
"For us it was a no-brainer," Arizona CEO and president Derrick Hall said. "When we got the letter, we wanted to do all we could."
In addition, this is a family the organization knows quite well. Not only had Aguirre regularly attended at least 20 games a year, he had celebrated several occasions at Chase Field.
It was as a season-ticket holder that Aguirre met his now ex-wife, Nikki. The mother of Aguirre's two children, Nikki had tickets in the row behind Aguirre. The ballpark was later the setting of Aguirre's proposal.
"There has been," as Aguirre put it, "a lot of history with my family made here."
On Monday it was all about his kids. Aguirre donned a D-backs uniform and catcher's gear, a disguise that would allow him to catch pitches from both of his children. Then he would reveal himself.
He took his position as Jackson and Alanna, their backs to home plate, watched their dad deliver his video message. They then turned and took turns throwing -- Jackson first, then Alanna.
Aguirre lifted his mask. And after briefly processing their dad's presence, both children were scooped up in his arms.
"I was thinking, 'That's Daddy, even when the mask was on,'" Alanna said afterward.
Said Jackson: "I didn't know it was my dad, even though he looks like him."
It was just as Aguirre had predicted. If anyone was going to recognize him in disguise, it would be his youngest, the analytical one.
The reunion continued in the tunnels of Chase Field after the family exited the field to sustained applause. As Aguirre knew she would, Alanna asked more questions, trying to figure out just how her father had pulled off such an extravagant surprise.
She jumped into his arms. Jackson took his father's hand.
Aguirre explained to them how he had left Afghanistan on Wednesday and, after a stop in Kyrgyzstan, arrived at the Phoenix airport on Sunday morning. Other family members and friends had reunited with him then, already knowing about the planned surprise.
The hardest part came in the hours that followed. Only miles away from his children, Aguirre knew that for the sake of suspense and surprise, he couldn't make contact.
Aguirre, who last month was periodically sneaking glances at D-backs games in an Afghanistan dining facility, is unsure whether he'll be called for deployment again. If he's asked, he'll willingly go, but Monday wasn't the time to ponder such possibilities.
As the cameras departed and the attention dissolved, he and his children continued to embrace. They then joined nearly 200 friends and family members in the stands for a night at the ballpark.
Certainly fitting, as baseball had always been what bonded them most.
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.