Threads do not set a OG image. As you can see below, threads are NOT passing in OG related arg data to the metadata macro (which means that the OG image being reported in the <head> is the SITE LOGO).
Code:
<xf:macro template="metadata_macros" name="metadata"
arg-description="{$fpSnippet}"
arg-shareUrl="{{ link('canonical:threads', $thread) }}"
arg-canonicalUrl="{{ link('canonical:threads', $thread, {'page': $page}) }}" />
What threads DO HAVE however are POSTS with IMAGES and sometimes, the Facebook Debuger (not always) will pick out one of those attachment images and use that as the OG image instead of the Site Logo (that is controlled by facebook tho, not XF).
There are also some 3rd party addons that do things like add Cover Image functionality to Threads, which includes reporting that cover image as the OG image. Also, I believe that in XF 2.2.0 RC 2, the new Article Threads are also setting an OG image if the Article Thread System determines that there is an acceptable image in the first post of the thread (nobody has seen that code yet as XF 2.2.0 RC 2 has not been released yet.... well, as I am tying this, they release RC 2 lol).
Sportsbook does have an ICON (Category Image), however, that is not something that can be set as an OG IMAGE as its too small (OG requires at least 400x400).
As I've said, the only thing currently that a Sportsbook event has that could even be used to set an OG image, would be the Category Icon, however, its TOO SMALL, so Facebook would REJECT it even if I did set it.
What might work for you RIGHT NOW is editing the template 'event_view' and pass in a custom image via arg-ImageUrl to set a custom OG image for Sportsbook.
This is what Sportsbook is using currently (which as you can see, is the same as threads).
Code:
<xf:macro template="metadata_macros" name="metadata"
arg-description="{$descSnippet}"
arg-shareUrl="{{ link('canonical:sportsbook', $event) }}"
arg-canonicalUrl="{{ link('canonical:sportsbook', $event, {'page': $page > 1 ? $page : null}) }}" />
Modifying it to pass in an image url and setting the twitter card to large (optional) might look a bit better than facebook displaying the site logo when sharing sportsbook events on Facebook.
Code:
<xf:macro template="metadata_macros" name="metadata"
arg-description="{$descSnippet}"
arg-shareUrl="{{ link('canonical:sportsbook', $event) }}"
arg-canonicalUrl="{{ link('canonical:sportsbook', $event, {'page': $page > 1 ? $page : null}) }}"
arg-imageUrl="{{ base_url('styles/default/xenaddons/sportsbook/category_images/sb_cover_image.png', true) }}"
arg-twitterCard="summary_large_image" />
Note: You'll need to upload your custom image to styles/default/xenaddons/sportsbook/category_images/image_name.extension as well as change the sb_cover_image.png to what ever your image name and extension is.
As for CHANGES in Sportsbook... there is at least 1 suggestion for being able set set a Cover Image (similar to AMS) and if that happens, I'd be adding in a generic cover image that would be used as the OG image if an event didn't have a cover image set.
