The Relay Breakdown: Men’s 4x100m Freestyle

by Sam Blacker 13

June 03rd, 2025 National, News

2025 U.S. NATIONAL CHAMPIONSHIPS

Men’s 100 Freestyle — Final

  • World Record: 46.40 — Pan Zhanle, China (2024)
  • American Record: 46.96 — Caeleb Dressel (2019)
  • U.S. Open record: 46.99 – Jack Alexy, United States (2025)
  • 2024 U.S. Olympic Trials Champion: Chris Guiliano — 47.38
  • World Aquatics ‘A’ Cut: 48.34

Top 8:

  1. Jack Alexy (CAL) – 47.17
  2. Patrick Sammon (SUN) – 47.47
  3. Chris Guiliano (TXLA) – 47.49
  4. Destin Lasco (CAL) – 47.58
  5. Jonny Kulow (SUN) – 47.82
  6. Shaine Casas (TXLA) – 47.92
  7. Henry McFadden (JW) – 47.97
  8. Grant House (SUN) – 48.01

The 100 freestyle final tonight was absolutely breathtakingly quick. For a second year in a row a 47.5 was not enough for an individual spot, whilst there are two men who broke 48 who will be left at home (Brooks Curry from the ‘B’ was the other).

The top four will be guaranteed a spot, whilst fifth and sixth will need to wait to see how the team shapes up elsewhere.

What does all this mean for Team USA’s 4×100 free relay this summer?

The Past Is History, the Future Is a Mystery?

Last year’s Olympic Trials featured an historic 100 freestyle final. Not only did the top four swimmers all break 48 seconds, a first, but all of the top six did. Their Trials times add-up of 3:10.16 would have been quick enough to win Olympic gold.

The US did just that in Paris in a time of 3:09.28, the sixth-fastest time in history, but the drop of 0.88 seconds was the smallest in recent history for the US

Here was what the gaps look like between the add-up from the top four at Nationals and the relay times swum later that summer since 2000.


The last two years have seen much smaller gaps than the previous decade. There may not be a trend there however – the 2023 team was a weak one, missing a true star (Jack Alexy only split 47.6 – his breakout later in the week was truly remarkable), and as mentioned the trials add-up in 2024 was quick enough to be a gold-medal contender already.

We love to predict how relays will perform before a major summer meet. There are almost no other real opportunities for a top-tier long course relay team to compete, so there’s limited data to go off.

Based on the U.S. Nationals results we’ve built a model to predict the final time for the American 4×100 free relay this summer. To calculate this we’ve considered the National Championship results (top four), previous history of the drops from Nationals to the relay in the summer, and the raw times themselves.

The past four years look something like this:

Year Trials Add-up Predicted Time Range (90% confidence band*) Range (50% confidence band) Actual Relay Time
2021 3:11.56 3:09.59 3:09.00 – 3:10.14 3:09.33 – 3:09.75 3:08.97
2022 3:12.26 3:10.05 3:09.53 – 3:10.48 3:09.71- 3:10.09 3:09.34
2023 3:11.90 3:09.82 3:09.28 – 3:10.29 3:09.51 – 3:09.89 3:10.81
2024 3:10.16 3:08.52 3:07.64 – 3:09.29 3:08.66 – 3:09.39 3:09.28

*This defines the upper and lower limits of a range in which we would be 90% sure that the result would fall – if this was raced 100 times, in 90 of those we’d expect a time in this range.

First things first, the model does have some limitations. It is only intended as a ballpark figure and the 90% and 50% confidence bands are too confident, especially for the last few years where the actual drops have ranged anywhere from 0.88 seconds to 2.92 seconds.

Overall though, we’re not looking for this to give us an absolute relay time to hold ourselves to for the summer – just a range which we (or you) can debate. Without further ado, here are all the numbers from this year’s trials you need to worry about.

The Numbers

Top 4
1 Jack Alexy – 47.17
2 Patrick Sammon – 47.47
3 Chris Guiliano – 47.49
4 Destin Lasco – 47.58
Total 3:09.71
Predicted time 3:08.86
Range (90% confidence band) 3:07.71 – 3:09.61
Range (50% confidence band) 3:08.57 – 3:09.31

 

Fastest three flat-start times of the top-six:

Place Swimmer #1 #2 #3
1 Jack Alexy 46.99 47.08 47.17
2 Patrick Sammon 47.47 47.78 48.18
3 Chris Guiliano 47.25 47.38 47.49
4 Destin Lasco 47.58 47.82 47.90
5 Jonny Kulow 47.82 47.82 48.35
6 Shaine Casas 47.92 48.23 48.24

 

Fastest three senior international relay splits of the top six:

Place Swimmer #1 #2 #3
1 Jack Alexy 47.00 47.48 47.56
2 Patrick Sammon 48.18
3 Chris Guiliano 47.33 47.77 48.18
4 Destin Lasco 47.95
5 Jonny Kulow 47.32 47.39 47.44
6 Shaine Casas 48.47

 

Fastest flat-start add-up:

Place Swimmer Time
1 Jack Alexy 46.99
2 Chris Guiliano 47.25
3 Patrick Sammon 47.47
4 Destin Lasco 47.58
Add-up 3:09.29

 

Fastest flat start + relay split add-up:

Place Swimmer Time
1 Jack Alexy 46.99
2 Chris Guiliano 47.25 (FS)
3 Jonny Kulow 47.32
4 Patrick Sammon 47.47 (FS)
Total Add-up 3:09.03

Jonny Kulow could be a weapon on this relay after three sub-47.5 splits back in 2023 at the Pan-American games. There is not a great deal of international relay experience from these six- Alexy and Guiliano are the only two to have swum in a worlds final – but based on raw speed alone they make a formidable team

As a final look ahead, here are the U.S. Nationals/Trials to summer relay drops since 2000 based on location. The circles get darker as the year gets later, and any hollow circles indicate a negative drop – that is, an increase.

 

 

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Former Big10
1 day ago

Sammon/Casas/Kulow/Lasco will be interesting to follow. Big opportunity for them.

LePatron
1 day ago

WR set by Phelps, Weber-Gale,Jones & Lezak at 3:08.24 in Beijing on August 11, 2008, which could be converted to a 47.06 mean leg split for a comparative purpose, is too tough to be out-touched at moment, unless one leg might swim a Panzhanle-esque split or on-par-with-Lezak one anyway.

Khachaturian
1 day ago

gonna average like 47.2 i do think this is gonna be one of the fastest in the decade

Justin Pollard
1 day ago

Come on. 3:07:71. LFG.

Wethorn
1 day ago

So in the historical view, in 3 of the 4 years the actual time was outside of the 90th percentile, and the 4th was 1/100th within? I’ll take the dog all day long.

I’m not a stats guy, but that seems odd. Perhaps the number of observations are so small that real statistical analysis isn’t appropriate?

Kevin
Reply to  Wethorn
1 day ago

I’m guessing the model was built on data going back to at least 2000 if not earlier. They presented data for other stats back to then for other categories just not for the prediction set. Could be wrong, but based on other stat articles they do tend to know what they are doing with sample sizes.

Khase Calisz
1 day ago

Who will they pick is the question. Is Johnny Kulow capable of something greater?

8108
Reply to  Khase Calisz
1 day ago

I bet they’ll use him in the prelims and he’ll light it up, he’s a huge relay swimmer

BR32
Reply to  8108
1 day ago

Looking forward to seeing it!

MDS
Reply to  Khase Calisz
1 day ago

Kulow’s been ASU’s “go to” relay anchor since his freshman year.

Anchored ASU 2025 400 SCY Medley relay at :39.93, all-time behind only the fellow in the next lane, Tennessee’s Jordan Crooks, who was :39.36. Dressell broke 40 individually but never on a relay.

And on LCM 100 relay splits, at the Pan Ams he assembled a list of :47.32, :47.39 and :47.44 in meet where he swam his flat start PB at :48.38. Pretty dang consistent.

Kulow is a dependable relay monster. Also a SCY 50 split PB of :17.78.

Sammon does not have as large a sample size but when given a leg was also very dependable, includng occasional flashes (like tonight). :40.34 on 2nd leg of… Read more »

Jason
1 day ago

Guiliano split 47.3 at Paris