Looking to build a very data-heavy content site and not sure if what I'm looking to do can be accomplished in WordPress (my preference) or even in Drupal for that matter. The problem isn't the content, which I assume Custom Post Types (or maybe Pods??) could do. It's the relationships between the content. Basically want to build pages for individual baseball players, with a some stats (not totally crazy, just basics), RSS headlines from various sites, photos, etc. but with relationships to teams, individual games played in, etc. That's where I'm unsure. Even in Drupal it looks like I would have to use the Entity reference module to accomplish this. So, player is on a team, a team plays in a game, etc. being able to sort and browse by these relationships. Thoughts on if WordPress (or Drupal, or other) is up to this or I would have to go complete custom app/framework? Thanks!
I would go with WordPress for the simple reason that it takes less time to create custom websites (your in a WordPress Support site did you think you would get a different answer?). It sounds like you need to read up on custom post types and taxonomies. I don't see why the requirements you've mentioned couldn't be handled by CPT's if you set it up right. Here are a few resources to some info that may help:
Justin Tadlock's CPT Tutorial (an older article, but still useful).
That should give you a good start on how to use CPT's and Taxonomies to catagorize your content into the needed fields.
tl;dr version: YES, both Wordpress and Drupal can do the job.
I've been in a similar situation. You can use both, in the end it's a matter of workflow and taste. You can do it in Drupal almost out of the box. Version 7 integrates Content Construction Kit (CCK) in which you can create custom content types - with custom field types, among which one is the node reference type. Just add the Views module for displaying and filtering content by these relationships.
Few years ago Drupal would've been the definite answer, but nowadays, since the introduction of Custom Fields, Custom Taxonomies and finally Custom Post Types you can achieve a similar structure in WordPress too, but it can take a bit more work (read: additional coding).
Now it depends also which you're more familiar with. People tend to agree that Drupal takes a steeper learning curve. Drupal is a powerhouse, this also means it's more complicated. WordPress has a smoother user experience - in terms of admin interface. Core and module updates are a breeze in WP, not the same goes for Drupal. Thus, as a personal taste I always try to solve my problems with WP.