For these controls to function you need to provide the markup for them, bootstrap doesn't add them to modals automatically. If you can modify the output of playerdetails.php, simply add the markup there...e.g.
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span></button>
<h4 class="modal-title">Modal title</h4>
</div>
However Bootstrap has deprecated the remote option since v3.3.0 and removed it alltogether in Bootstrap 4. Instead they recommend instead using client-side templating or a data binding framework, or calling jQuery.load yourself
If you call jQuery.load yourself you can do something like this:
<!-- Modal HTML -->
<div id="myModal" class="modal fade">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">×</span></button>
<h4 class="modal-title">Modal title</h4>
</div>
<div class="modal-body">
<!-- load contents here -->
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
<button type="button" class="btn btn-primary">Save changes</button>
</div>
</div>
</div>
</div>
define your button
<button class="btn btn-lg btn-primary btn-open-dialog">Launch Demo Modal</button>
and bind a jQuery click event to it to load your player
$('.btn-open-dialog').on('click', function(){
$('#myModal .modal-body').load('playerdetails.php?player=99VY9JR8', function(){
/* load finished, show dialog */
$('#myModal').modal('show')
});
});