Full code after the jump.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/10/15/rotating-labels-in-a-flex-chart-axis-using-the-labelrotation-style/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Style>
        @font-face {
            src: local("Arial");
            font-family: EmbeddedArial;
        }

        BarChart {
            font-family: EmbeddedArial;
        }
    </mx:Style>

    <mx:ArrayCollection id="arrColl">
        <mx:source>
            <mx:Array>
                <mx:Object name="R Winn" obp=".353" slg=".445" avg=".300" />
                <mx:Object name="P Feliz" obp=".290" slg=".418" avg=".253" />
                <mx:Object name="O Vizquel" obp=".305" slg=".316" avg=".246" />
                <mx:Object name="B Molina" obp=".298" slg=".433" avg=".276" />
                <mx:Object name="R Durham" obp=".295" slg=".343" avg=".218" />
            </mx:Array>
        </mx:source>
    </mx:ArrayCollection>

    <mx:ApplicationControlBar dock="true">
        <mx:Form>
            <mx:FormHeading label="labelRotation" />
            <mx:FormItem label="horizontalAxisRenderer:">
                <mx:HSlider id="horizontalLabelRotation"
                        minimum="-90"
                        maximum="90"
                        value="0"
                        liveDragging="true"
                        snapInterval="10"
                        tickInterval="10" />
            </mx:FormItem>
            <mx:FormItem label="verticalAxisRenderer:">
                <mx:HSlider id="verticalLabelRotation"
                        minimum="-90"
                        maximum="90"
                        value="0"
                        liveDragging="true"
                        snapInterval="10"
                        tickInterval="10" />
            </mx:FormItem>
        </mx:Form>

        <mx:Spacer width="100%" />

        <mx:Legend dataProvider="{barChart}"/>
    </mx:ApplicationControlBar>

    <mx:BarChart id="barChart"
             showDataTips="true"
             dataProvider="{arrColl}"
             width="100%"
             height="100%">

        <!-- vertical axis -->
        <mx:verticalAxis>
            <mx:CategoryAxis categoryField="name" title="Player"/>
        </mx:verticalAxis>

        <!-- vertical axis renderer -->
        <mx:verticalAxisRenderer>
            <mx:AxisRenderer labelRotation="{verticalLabelRotation.value}" />
        </mx:verticalAxisRenderer>

        <!-- horizontal axis renderer -->
        <mx:horizontalAxisRenderer>
            <mx:AxisRenderer labelRotation="{horizontalLabelRotation.value}" />
        </mx:horizontalAxisRenderer>

        <!-- series -->
        <mx:series>
            <mx:BarSeries id="obpSeries"
                    yField="name"
                    xField="obp"
                    displayName="obp" />
            <mx:BarSeries id="slgSeries"
                    yField="name"
                    xField="slg"
                    displayName="slg" />
            <mx:BarSeries id="avgSeries"
                    yField="name"
                    xField="avg"
                    displayName="avg" />
        </mx:series>
    </mx:BarChart>

</mx:Application>

View source is enabled in the following example.