SAN DIEGO — The stolen base is a lost art in baseball, and that is one reason why Mickey Morandini occasionally summons one of his players to first base hours before a game. The Phillies first base coach brings a baseball with him. He stands in front of the runner, holds the ball in the air, then drops it.

"I don't like guys who try to time pitchers," Morandini said. "That's where most of our pickoffs come from. They get caught trying to time them. This drill forces them to react when my hand drops. They're not allowed to move until my hand drops."

The progress is slow; the Phillies entered Monday's game on pace to record their fewest stolen bases in a season since 1973. They are in danger of not having a player with 20 stolen bases for the first time since 1997. The runner with their third-most steals is Howie Kendrick, who appeared in 39 games and was traded more than two weeks ago.

The Phillies, whether by design or not, have followed a trend prevalent in Major League Baseball. The stolen base is less of a weapon. Major-league teams are on pace for the fewest amount of stolen base attempts in a non-strike season since 1973, when there were 24 teams.

"I just don't think it's a big part of the game anymore," said Morandini, who oversees the Phillies' running game. "It's more about hitting the long ball and waiting for that big hit."

A lack of stolen bases is far from this roster's biggest issue. It is just one of many. There are reasons to explain the stolen-base decline: The Phillies do not reach base at a high rate; they play from behind in many games and are less apt to attempt a steal; their lineup is filled with plodding runners who move from station to station.

But there are capable threats. Cesar Hernandez and Odubel Herrera are blessed with quickness. Freddy Galvis can steal. Aaron Altherr and Nick Williams have displayed above-average speed.

A fast runner does not always equate to stolen bases.

Morandini, rather than stressing about the low totals, pointed to the team's 70 percent success rate, which ranked in the bottom half of the league, but not far from the 73 percent average. Hernandez, no doubt, has displayed improved instincts on the bases. He was successful on 17 of his 30 stolen-base attempts (57 percent) last season. That rate has jumped to 80 percent (12 of 15) in 2017.

"His instincts have been better," Morandini said.

The next step is applying some more aggressiveness. Hernandez, Morandini said, should be a 20-25 stolen-base guy. Hernandez may have reached that in 2017 if not for six weeks on the disabled list with an abdominal injury.

Hernandez said more video work and advice from Morandini has helped him find better spots to run.

"I only go only when I'm sure I can get it," Hernandez said. "Years before, I went and I didn't care if I made an out or I was safe. This year, I'm more selective."

Earlier this month, Morandini asked Williams to accompany him to first base at Citizens Bank Park. They practiced the drill. Williams, despite his quickness, was not a base-stealer in the minors. His highest total was 15, in rookie ball.

"When I did that, I was just aggressive," Williams said. "Even when they slide step, I can beat it — if I left right when they're going. If I counted them. I could sit in the dugout and time them. The years I stole a lot of bases, I just said, 'OK, I'm going.' "

It is a bit more nuanced in the majors. Williams had attempted two steals before Monday's game. Both were unsuccessful.

"I had terrible jumps," Williams said.

Herrera is the one runner that has puzzled Morandini. He stole 25 bases in 32 attempts last season. He has swiped just seven in 12 chances in 2017. He is running less; a putrid May followed by a streak of extra-base hits in June limited the opportunities. But that's not a good enough excuse, Morandini said.

He likes that Herrera is aggressive, even if it is too aggressive as demonstrated by his mistakes. The next step is picking the correct spots.

"Baserunning is hard to practice," Morandini said. "Pitchers can throw their bullpen sessions and hitters can take as much batting practice as they want. But you can't simulate game speed with baserunning. You really can't. So, really, all you can do is stress it in spring training. We do a lot of things. It's hard during the season."

For now, it is low on the list of priorities — the game has deemphasized stealing bases. But Morandini envisions a day when teams accentuate it again.

"I think it'll come in cycles," Morandini said. "Teams are really trying to control the running game."

Extra bases

Mark Leiter Jr. will replace Vince Velasquez in the rotation and start Tuesday's game. Velasquez underwent more tests Monday on his injured right middle finger, Phillies manager Pete Mackanin said, including a magnetic resonance angiogram. … Rhys Hoskins started his fourth game in left field. The rookie has not yet been a liability at his temporary position. "Pleasantly surprised," Mackanin said. "He looks sure-handed out there. That's half the battle. He hasn't been tested range-wise. So I'm anxious to see that."