INDIANAPOLIS – Forget the bottom line.

Ignore the fact the Indianapolis Colts lost their preseason opener to Buffalo Saturday in Highmark Stadium — OK, the actual bottom line was 23-19 — and now have dropped seven straight to the Bills in the preseason/insignificant series.

The major takeaway: Anthony Richardson took the next step on a path that must result in him emerging as the Colts’ latest quarterback of the future. It was just his 14th NFL/college start.

It wasn’t as dramatic as the NFL debuts of the most recent quarterbacks of the future, each the No. 1 overall pick in the draft.

Peyton Manning’s first pro pass was a 48-yard touchdown to Marvin Harrison Aug. 8, 1998 at Seattle. Andrew Luck delivered his Aug. 12, 2012 against the Los Angeles Rams, an innocent dump-off running back Donald Brown turned into a 63-yard TD.

Eleven years after Luck burst on the scene, it was Richardson’s turn. The No. 4 overall pick in the April draft directed the first three drives against a good portion of a Bills defense that ranked No. 6 in the league a year ago, but was unable to generate points.

But any snap judgment of Richardson must be done with a wide lens and all the facts. First steps are rarely pleasing to the eye, Manning and Luck notwithstanding.

“Overall I think I did a pretty good job (but) I can do a lot better,’’ Richardson said during a sideline interview on the CBS4 broadcast. “My first time getting official NFL reps . . . I’m excited.

“I’ve still gotta improve. Lot of room for improvement. I’m just excited I even got the chance to go out there.’’

Richardson opened by completing 5 and 4-yard passes to Isaiah McKenzie, then watched as his third attempt to the right between Alec Pierce and McKenzie — hurried and somewhat off balance — was intercepted by Dane Jackson.

The early mistake got his attention. It was Richardson’s only glaring miscue during a 7-of-12, 67-yard afternoon.

“I can’t be reckless with the ball,’’ he said.

Lest anyone pile on the rookie for being careless with the football, McKenzie took the blame. That might have been the reason position coach Reggie Wayne addressed him on the sideline.

“The interception was on me,’’ McKenzie said during the broadcast. “Miscommunication.’’

His message to Richardson on the bench?

“Just keep ballin’. That’s on me,’’ he said.

Richardson listened and moved on. His second and third drives were promising — a total of 21 plays, 118 yards and eight first downs — even though neither resulted in points.

“We got off the field pretty quick the first drive,’’ he said. “It felt good just getting back in the groove and pushing the ball down the field and let us know where we’re at.

At the risk of being a Richardson apologist, his teammates didn’t exactly help him out.

The second drive reached a third-and-2 at the Buffalo 41, but fizzled when rookie Evan Hull burrowed for 1 yard and was stuffed for no gain on fourth-and-1.

The third drive was almost as good at it gets. Almost.

Richardson found himself backed up at his own 7, but meticulously moved the Colts down the field. Ten yards to Hull, 20 to tight end Kylen Granson and 11 to McKenzie, with several rushing attempts by Deon Jackson mixed in.

But there were too many botched opportunities.

Richardson delivered a perfect pass to Pierce, who was tightly covered by Siran Neal near the right pylon. Instead of a 34-yard TD or a first-and-goal inside the 1, Pierce was unable to secure the football. His disappointment was obvious.

Four plays later from the Bills 12, Richardson ran an RPO around the left side and was shoved out of bounds inside the 5. Instead of a first-and-goal, a downfield holding penalty against tight end Pharoah Brown pushed the Colts back to first-and-18 at the 20.

The capper came when Matt Gay pulled a 28-yard field goal wide left and it glanced off the upright. The veteran kicker, signed to a four-year, $22.5 million contract in the offseason, also missed a PAT.

Shaq’s back

The next step in Shaquille Leonard’s comeback from a second surgery on his back was quietly important. The All-Pro linebacker was on the field for five plays – six if you count one nullified by a penalty – and was credited with zero sacks.

Didn’t matter.

“Aw man, it was amazing,’’ Leonard said during the broadcast. “This was the biggest step, just getting back in the game and the fire, man, and getting my feet and my confidence and everything back up under me.’’

All that was missing was a play or two that required pounding a ballcarrier.

“Today was hard,’’ he said. “A lot of plays went away, so I really didn’t get too much contact. (But) speed don’t change. I was definitely confident getting back out there.’’

Caught in the Rush

Rookie Darius Rush has been pushing for serious playing time at cornerback during training camp, and Saturday couldn’t have hurt his chances.

The fifth-round draft pick out of South Carolina gathered in a Jeff Allen pass that went off the hands of Tyrell Shavers and returned it 52 yards for a touchdown.

Tracking the QBs

After Richardson’s debut, Gardner Minshew II and Sam Ehlinger finished up.

Minshew’s afternoon started with him absorbing sacks on his first two plays. But he recovered on his second possession and drove the Colts 88 yards in 12 plays that ended with Jake Funk’s 1-yard TD run at the end of the second quarter.

Minshew finished 6-of-6 for 72 yards and a 116.7 rating.

Ehlinger completed 8-of-9 for 72 yards and a 100.0 rating. He brought the Colts to within 23-19 with 3:59 remaining with a 7-play, 76-yard drive.

Jason Huntley, who was signed Wednesday, capped the drive with a 3-yard TD.

This and that

Twelve different players caught at least one pass. Malik Turner led the way with four catches for 48 yards, followed by McKenzie’s three receptions for 20 yards.

Rookie Josh Downs continued his preseason push to be the Colts’ top slot receiver with two catches for 29 yards, including an 18 yarder.

Linebacker Grant Stuard led the defense with 10 tackles and added a special teams tackle. Cornerback Kevin Tolliver II and linebacker Sequn Olubi had five each.

The defense came up with three sacks: Dayo Odeyingbo, Al-Quadin Muhammad and Khalid Kareem.