Did my traffic really drop?

Nothing. A drop that size is worth investigating straight away.
It may deserve a look, but these totals cover different numbers of days, so they can't tell you yet how much traffic changed. Check the dates first.

They cover different numbers of days.
September is a full month; October has 23 days in this data. Matching the dates still gives 375 clicks for September 1 to 23 against 182 for October 1 to 23, so October is lower even on the same dates. Keep going.

Clicks are the wrong measure; look at impressions instead.
Impressions are worth reading, but they have the same problem: the months are different lengths. Fix the comparison first, then choose the measure.

Clicks per day, September against October.
That corrects for the number of days, but one big day still pulls the average up. Use it as a first description, then look at which dates and pages make up the change.

Game days against game days, and ordinary days against ordinary days.
The table below groups the same kinds of day and leaves out the opener and the day after it, so one game doesn't dominate. Per day, October's Mondays to Thursdays are about the same, its other Fridays to Sundays are about the same, and its game days are higher. These averages describe only these selected days; small groups and exclusions do not establish a normal level or explain the change. That narrows where to look, not why it happened. Next, check which pages lost clicks.

Wait for the full October before comparing anything.
You can compare the dates you already have now, as long as you say October isn't complete and that its newest days, October 22 and 23, may still rise. A full month will sharpen the comparison but won't explain a change by itself.

The roster page slipped in the results, so it needs rewriting.
Fewer impressions don't show a ranking loss or a problem with the page. Compare the same searches and their positions, and read the page, before choosing a fix.

The roster page's average position stayed about the same, so its rankings held.
Average position is the average spot the page held across the searches it appeared for. A steady average can hide a change in which searches the page appears for: a page can drop out of one search while its average across the others stays the same. Look at the individual searches before ruling out a ranking change.

Impressions fell, and the cause isn't clear yet.
That's an honest description. Make it useful by naming the next check: compare the same searches on both dates, then read the page.

Compare the searches on both dates and read the page before choosing a change.
The search table shows what makes up each total. On October 10, one search, “oregon qb depth chart”, gave the page 395 of those impressions. On October 17 that search isn't in the export at all. That's the lead: what changed for that search, and does the page still answer it? A search missing from the export doesn't mean nobody searched it.