The fact Utley's rehab has reached a "plateau" simply means his knees have not improved and he remains in pain. That is especially concerning because he has not played since Game 5 of the 2011 National League Division Series on Oct. 7.
The Phillies said last month they planned to bring Utley along slowly this spring, but he had not appeared in a single Grapefruit League game or participated in fielding practice since late February.
Those have been red flags for weeks.
Phillies manager Charlie Manuel raised another one late last week, when he offered a candid assessment of his second baseman's health: "His problem is not going away. More than likely it maybe never goes away. ... Will he ever be 100 percent? I don't know about that. He might never be that."
And that has the Phillies and their fans understandably concerned about Utley's future.
Utley had a combined .911 on-base-plus-slugging percentage from 2005-10, when he was a five-time National League All-Star and had Hall of Famers like Joe Morgan calling him the best offensive second baseman in baseball history. Utley's OPS over that six-year span ranked 14th out of 210 qualifying players.
But with a knee condition that sapped him of his lower body strength, Utley hit just .259 with 11 home runs, 44 RBIs and a pedestrian .769 OPS in 103 games last year. Last season's OPS would have ranked 77th out of 145 players, if he had enough plate appearances to qualify.
How much are the Phillies worried about Utley's career?
"I worry about Chase because it's a chronic knee problem," Amaro said. "About his career? I don't know."
But is it realistic to think Utley can return to prior form, considering his knee problems are not going away?
"I couldn't even really speculate," Amaro said. "All I hope is that he's back and healthy and playing on our club."
Just last week, Amaro and Utley offered encouraging health updates. Amaro said Thursday, "I don't think there's any chance he won't be ready Opening Day," while Utley said Saturday, "We're making progress. I hope to be on the field next week."
So what changed?
"I don't know if anything changed," Amaro said. "He just didn't progress as we would have liked to have him progress. When he first came into spring, he was feeling really good. He was taking ground balls, and then he started to feel it a bit more."
Amaro would not name the specialist at Utley's request, but Amaro said Utley is not leaving the country or having any type of surgical procedure. In fact, Amaro said the Phillies and Utley have not discussed surgery.
But it is important to note the issue is in both knees, not just his right knee, which was the case last spring. Amaro said Utley's right knee actually feels a bit better than his left.
"The guy's got bad knees. We know it," Amaro said. "And that's a fact, and we're just trying to limit [his workload] and also make sure that he's ready to go and feeling comfortable about the bulk of the season."
The Phillies already had been looking to upgrade their infield depth before Monday's announcement, but Amaro insisted Monday they have no plans to find help from outside the organization. He essentially anointed Freddy Galvis the Opening Day second baseman. Galvis has impressed the front office and coaching staff this spring.
But with Ryan Howard, who is recovering from a left Achilles injury, and Utley both opening the season on the disabled list, the Phillies are certainly lacking in the infield and lineup.
"Not a lot of offense, huh?" Amaro said. "That strikes at our offense. We're going to have to pitch the ball and catch the ball like we did last year."
"You get dealt bad blows," Manuel said. "You have to overcome it. You have to keep playing. You have to try to find someone to fill in and hopefully they'll do a job for you. We've been very fortunate with that ever since I've been here. But at the same time, Utley and Howard, that's a heavy load."
Utley has been the team's No. 3 hitter since he became an everyday player. Manuel said after Monday's 4-3 victory over the Tigers that he does not know who his No. 3 hitter might be, although Shane Victorino and Hunter Pence seem to be the top two candidates.
The Phillies won 102 games last season with Utley missing the season's first 46 games. But this feels different. The weaknesses look a little bigger this time.
"Well, we've lost a lot. That's the truth," Phillies shortstop Jimmy Rollins said. "But we've got to keep going forward. We still have a good team. It's not the same by any means, but I'm not discounting our chances. It's going to be different. We didn't have a great team in '07 and we didn't have a great team in '08, but we found ways to win. We're kind of back there. Back then, it was the [pitching] staff was always hurt. Now it's the guys with the bats. We're going to have to find a way to execute, urgency on winning and those things are going to be more important because we have lost a lot of pop and a lot of good situational hitters."
Few have been better when healthy than Utley.
Rollins believes he'll play alongside him again.
"Again? Yeah," Rollins said. "Until we hear otherwise. I don't know the severity of what's going on, other than he's not playing. I don't know any details.
"If he doesn't play again that would be something horrible. That would be horrible. But I don't see it that way. At least I hope that's not the case. That would be bad."